Fireballs and Meteorites - SOTT.NET

January 2010

2010-01-02T07:18:00.000Z

Russia Considering Sending Spacecraft to Knock Asteroid Off Path And Prevent Earth Collision

Vladimir Isachenkov

The Associated Press
Wed, 30 Dec 2009 13:50 EST

Russia is considering sending a spacecraft to a large asteroid to knock it off its path and prevent its collision with Earth - a collision NASA considers highly unlikely - the head of the country's space agency said Wednesday.

Anatoly Perminov said the space agency will hold a meeting soon to assess a mission to Apophis, telling Golos Rossii radio that it would invite NASA, the European Space Agency, the Chinese space agency and others to join the project once it is finalized.

When the 270-meter (885-foot) asteroid was first discovered in 2004, astronomers estimated the chances of it smashing into Earth in its first flyby in 2029 were as high as 1-in-37, but have since lowered their estimate.

Further studies ruled out the possibility of an impact in 2029, when the asteroid is expected to come no closer than 18,300 miles (29,450 kilometres) above Earth's surface, but they indicated a small possibility of a hit on subsequent encounters.

In October, NASA lowered the odds that Apophis could hit Earth in 2036 from a 1-in-45,000 as earlier thought to a 1-in-250,000 chance after researchers recalculated the asteroid's path. It said another close encounter in 2068 will involve a 1-in-330,000 chance of impact.

"It wasn't anything to worry about before. Now it's even less so," said Steve Chesley, an astronomer with the Near Earth Object Program at NASA's Jet Propulsion Laboratory.

Without mentioning NASA conclusions, Perminov said that he heard from a scientist that Apophis is getting closer and may hit the planet. "I don't remember exactly, but it seems to me it could hit the Earth by 2032," Perminov said.

"People's lives are at stake. We should pay several hundred million dollars and build a system that would allow to prevent a collision, rather than sit and wait for it to happen and kill hundreds of thousands of people," Perminov said.

Scientists have long theorized about asteroid deflection strategies. Some have proposed sending a probe to circle around a dangerous asteroid to gradually change its trajectory. Others suggested sending a spacecraft to collide with the asteroid and alter its momentum, or using nuclear weapons to hit it.

Perminov wouldn't disclose any details of the project, saying they still need to be worked out. But he said the mission wouldn't require any nuclear explosions.

Hollywood action films Deep Impact and Armageddon, have featured space missions scrambling to avoid catastrophic collisions. In both movies space crews use nuclear bombs in an attempt to prevent collisions.

"Calculations show that it's possible to create a special purpose spacecraft within the time we have, which would help avoid the collision without destroying it (the asteroid) and without detonating any nuclear charges," Perminov said. "The threat of collision can be averted."

Boris Shustov, the director of the Institute of Astronomy under the Russian Academy of Sciences, hailed Perminov's statement as a signal that officials had come to recognize the danger posed by asteroids.

"Apophis is just a symbolic example, there are many other dangerous objects we know little about," he said, according to RIA Novosti news agency.

Comment: What is wrong with this picture? We are being told that the chance of Apophis hitting Earth is 1-in-250,000 - yet the Russians are considering spending the money to send it off course. That means one of two things: either the odds are much higher than we are told, or there is something else of concern out there and Apophis is just the cover story.

England: Whole valley lights up in a semi-circle - nothing seen

Andy Mannion

UK UFO Sightings
Wed, 30 Dec 2009 17:43 EST

Posted: December 30, 2009

Location of Sighting: County Durham A688 between Bishop Auckland and Spennymoor
Date of Sighting: 30/12/2009
Time: 6:13am

Witness Statement: I was driving towards Spennymoor this morning and had passed Bishop Auckland, and was passed the Park Head hotel, up hte hill, almost to the Petrol Station (on the right) when the whole valley on my left lit up in a huge semi-circle arc shape, with a huge bright light...(to be honest, expected a huge explosion after it, but nothing happened, except for me being terrified )

December 2009

2009-12-15T06:31:00.004Z

US: "Electric" Blue Streak (Meteor?) Seen in Eastern Sky

UFOs Northwest

Thu, 03 Dec 2009 18:58 EST

Posted: December 2, 2009

Date of Sighting: November 29, 2009
Time of Sighting: 12:05 to 12:10 AM PST
Location of Sighting: Longview, Washington (Southwestern Washington)

Description: I saw an electric blue streak in the eastern sky. The object was about 1 & 1/2 times the size of the moon at that time. The object was about an inch to the left of the moon, which was visually about a foot above the horizon. I noticed the object when it was at about the height the moon was at this point. It descended towards the horizon in a straight line lasting 1 to 2 seconds although the tail did not really appear to be tapering. I immediately thought meteorite & half expected to hear it impact somewhere east of Longview, Washington. My impression was of a round electric blue, large object moving toward the eastern sky in very rapid stages. Was this a meteorite? I have never seen this color nor an object other than the moon of this size in the sky.

Note: I suspect that the witness saw a meteor. Most meteors are green, red or orange in color. A few meteors are greenish-blue or blue in color. No meteors were reported to the American Meteor Society web site on this date, but this does not mean that no meteors were in the sky on the above date and time.

Mystery as spiral blue light display hovers above Norway

Daily Mail

Wed, 09 Dec 2009 10:57 EST

© Rex Features
Strange spiral: Residents in northern Norway were left stunned after the lightshow, which almost looked computer-generated, appeared in the skies above them

A mysterious light display appearing over Norway last night has left thousands of residents in the north of the country baffled.

Witnesses from Trøndelag to Finnmark compared the amazing sight to anything from a Russian rocket to a meteor or a shock wave - although no one appears to have mentioned UFOs yet.

The phenomenon began when what appeared to be a blue light seemed to soar up from behind a mountain. It stopped mid-air, then began to circulate.

Within seconds a giant spiral had covered the entire sky. Then a green-blue beam of light shot out from its centre - lasting for ten to twelve minutes before disappearing completely.

The Norwegian Meteorological Institute was flooded with telephone calls after the light storm - which astronomers have said did not appear to have been connected to the aurora, or Northern Lights, so common in that area of the world.

Fred Hansen, from Bø in Vesterålen, described the sight as 'like a big fireball that went around, with a great light around it again.'

'It spun and exploded in the sky,' Totto Eriksen from Tromsø told VG Nett.

He spotted the lights as he walked his daughter Amalie to school.

He said: 'We saw it from the Inner Harbor in Tromsø. It was absolutely fantastic.

'It almost looked like a rocket that spun around and around and then went diagonally down the heavens.

'It looked like the moon was coming over the mountain, but then came something completely different.'

'It was like a giant spiral - a shooting star that spun around and around. I initially thought it was a projector', added Axel Rose Berg, from Alta.

Celebrity astronomer Knut Jørgen Røed Ødegaard told VG Nett he had never seen anything like the lights.

He said: 'My first thought was that it was a fireball meteor, but it has lasted far too long.

'It may have been a missile in Russia, but I can not guarantee that it is the answer.'

Air Traffic control in Tromsø claimed the light show lasted for two minutes, but admitted that was 'far too long to be an astronomical phenomena.'

Tromsø Geophysical Observatory researcher Truls Lynne Hansen was certain the light had been caused by a missile launch.

He told Norwegian media that the missile had likely lost control and exploded. The spiral, he claimed, was the result of light reflecting on the leaking fuel. He was quoted as saying the light was sunlight, despite the strange lights showing up at night.

The Barents Observer quoted Norwegian Defence spokesman Jon Espen Lien as saying that the Norwegian military does not know what the lights were - but that they were probably from a Russian missile.

He said it was normal for Russia to use the White Sea and the Barents Sea as a testing ground for missiles.

Bluish-green fireball sighted over northern Germany

Tue, 08 Dec 2009 12:10 EST

Deutsche Presse-Agentur/The Local

Several eyewitnesses reported seeing a bluish-green fireball over northern Germany on Monday night - possibly a large meteor burning up in the Earth's atmosphere, according to experts at the German Aerospace Centre (DLR).

The object was first sighted over Braunschweig around 11:40 pm, but people in Celle, Delmenhorst, Lüneburg, Grabow, Kiel and Hannover also spotted the fireball streaking across the sky. The Network for Researching Unusual Heavenly Phenomena (CENAP) said on Tuesday the object eventually broke up into brightly glowing pieces before disappearing.

Wilfried Tost from the DLR said the fireball was likely a meteor, explaining that on average one falls to Earth over Central Europe each month.

Last spring, a German meteorite researcher found the remains of another spectacular fireball on the Danish island of Lolland.

A German boy this summer also claimed he was hit in the hand by a pebble-sized meteorite as he was on his way to school.

Hawaii: Colored 'fireballs' light up evening sky

Coco Zickos

The Garden Island
Fri, 11 Dec 2009 11:29 EST

Wailua - Residents are still talking about the unique light show they witnessed in the evening skies last week.

A "big ol' honking fireball" was what Steve Yoder said he saw while he was on his way to Wailua from Waimea the night of Dec. 2. A "flaming green" object lit up the eastern sky right before 9 p.m.

"I hadn't started drinking yet," he said with a laugh.

In fact, Yoder said he found it hard to believe there has not yet been an explanation for what he saw, much like the loud noise over Kalaheo reported by residents in May of this year.

"I've seen meteorites all my life," he said. But added that what he saw was much different. "It was either a gigantic asteroid or one of the biggest meteorites I have ever seen."

About the size of a dime in the sky, it traveled at a downward angle for less than five seconds until it disappeared into the horizon, he said.

Residents as far as Anahola also reported seeing similar "orange and green" objects beginning around dusk the same evening, "some of them hovering over car ports in Anahola," said an Eastside resident who wished to remain anonymous.

The observer was one of many Eastside residents, particularly in the Waipouli and Wailua Homesteads areas, who saw unusual activity occurring around 8 p.m.

"There was an incredible number of shooting stars that night," they added. "We always have beautiful stars dashing everywhere, but this was an amazing sight."

"PMRF did not have any range operations, either on land or in the air on the evening of Dec. 2," wrote Pacific Missile Range Facility's spokesperson Tom Clements. "As a reminder, we also did not have operations on the evening that the (possibly jet) noise was heard over Kalaheo."

University of Hawai'i Professor of Astronomy Dr. Gareth Wynn-Williams said what witnesses are describing "certainly sounds like a large meteor."

"While it's always a thrill to see one, they are not all that uncommon and they don't get centrally recorded anywhere, as far as I know," he wrote in an e-mail Thursday. "But if you were to see part of it actually hit the ground, it would be well worth searching for the meteorite itself."

What one observes in the sky is actually called a meteor and is referenced as a meteorite when it hits the ground, he added.

"Only the very largest meteors make it through to be meteorites," he said.

Whether or not the objects seen were actually meteors, they continue to be unidentified. However, "the most reliable meteor shower of the year," according to Skyscrapers Inc., is set to peak this weekend.

More than 100 meteors can be seen per hour during the Geminids meteor shower and it should be "a great show for Hawai'i," according to gohawaii.com.

The shower can occur between Dec. 7 and Dec. 17, but peaks Dec. 13 and 14.

Huge fireball and blue/green skies seen from Minnesota to Wisconsin

Dave Olson

INFORUM
Fri, 11 Dec 2009 11:48 EST

Finding that the sky is blue is not unusual, unless it's 1:15 in the morning.

That's what happened early Friday when observers from western Minnesota to northern Wisconsin reported seeing a bright blue or green flash in the sky.

The National Weather Service in Grand Forks, North Dakota, logged a call at 1:25 a.m. from someone 15 miles west of Bemidji, Minnesota, who reported the sky looked green.

The weather station then heard from a sister station in Duluth, Minn., which passed along observations from law enforcement agencies in Wisconsin, where a huge fireball was seen near the town of Fifield that created temporary mid-day brightness, said Bill Barrett, a Weather Service official in Grand Forks.

Officials suspect the phenomena was a meteor, as this week marks the peak of the Geminid meteor shower, Barrett said.

A Becker County Sheriff's Department deputy was dispatched to investigate two reports of lights in the sky about 1:36 a.m., Sheriff Tim Gordon said.

The reports came from Highway 10 near Frazee, Minn., and Highway 34 east of Detroit Lakes.

Nothing was found, but the area was checked to make sure it wasn't a downed plane, Gordon said.

Gordon said there was ice fog in the sky and it's likely that whatever the object was, it appeared to be closer to the earth than it actually was.

He said the sheriff's department received similar reports of lights in the sky about a month ago, when weather conditions were similar and another meteor shower was occurring.

There have been other strange lights in the sky in recent days and weeks.

Earlier in the week, a bright ball of blue light spotted over Norway, which was also caught on video, is now believed to have been a Russian missile test that went bad.

In early December, a bright ball of fire was seen over one of the Hawaiian islands. A meteor is suspected in that sighting.

Geminid meteors will create a sky show Sunday night

Space Weather

Sat, 12 Dec 2009 22:41 EST

This weekend, Earth is passing through a stream of debris from extinct comet 3200 Phaethon, source of the annual Geminid meteor shower. Forecasters expect more than 100 meteors per hour to fly out of the constellation Gemini when the shower peaks on Dec. 13th and 14th. For most observers, the best time to look will be from 10 pm local time on Sunday night to dawn on Monday morning.

Click here to watch an early-arriving Geminid streak past the Moon on Dec. 9th.

"That was a good one," says NASA astronomer Bill Cooke, who recorded the meteor using an all-sky camera at the Marshall Space Flight Center in Huntsville, Alabama. "We should see many more this weekend." Cooke and colleagues are broadcasting a live video feed from their camera, which will monitor the skies over Huntsville throughout the Geminid meteor shower. The soundtrack is a 55 MHz forward-scatter meteor radar located near the optical camera.

Got clouds? If you can't see the Geminid meteor shower, try listening instead. The US Air Force Space Surveillance Radar is scanning the skies above Texas, and when a meteor passes overhead--ping!--there is an echo. Tune into Spaceweather Radio for live audio.

Canada: Apparent Meteor Zips Through Sky

Danny Grummett

News Talk 650 CKOM
Sat, 12 Dec 2009 16:46 EST

A trail of gold. That's what a Langham women said an apparent meteor left behind when it zipped across the Saskatchewan night sky. Laurie Suiker says she was driving home just before 6:00 Friday evening on Highway 16, near Lutheran Road, when she saw a flash of light. She initially thought it was a shooting star.

"I watched it trail for a tiny bit and then it went, poof !" said Suiker. "And there was this beautiful golden shower. It wasn't huge. It was way up there, but it was pretty beautiful."

Suiker described the flash for her husband, Chris, and compared it to the meteor sighting in November of 2008 near the Alberta/Saskatchewan border (Flash pictured right).

"It was not even close to that, but it was still pretty nice to see. It didn't light up the whole sky or anything. I watched (the trail) for about four minutes."

Meantime, one astronomy enthusiast said Suiker's sighting isn't surprising. Gary Stone, former president of the Royal Astronomical Society in Saskatoon,said the Earth always passes through comet debris this time of year.

"Being that it's near the peak of the Geminid meteor shower, it's quite likely it's an early one." said Stone. He added people should look to the Saskatchewan sky this weekend, as they could see quite the show in throughout Sunday morning, evening, and Monday morning. He's expecting to see 120 to 140 meteors an hour at the peak, most no bigger than a kernel of corn, but still visible to the naked eye.

Comment: A comment posted by a reader to the original article stated:

Saw something appearing...

On December 13th, 2009 LeRyck (not verified) says:

I am from Quebec city. Saturday evening, at 17:50 local time, I saw a quite big green ball streaking through the sky from East to West or possible from ENE to WSW. It was followed by a reddish tail. The whole experience did not last more than about 2 seconds. I saw it through a window. I roughly estimated its speed to 20,000 km/s.
Does anybody else have seen that?

Infrared space telescope launched from California

Steve Gorman, Dan Whitcomb and Cynthia Osterman

Reuters
Mon, 14 Dec 2009 16:26 EST

NASA's new infrared space telescope was launched into orbit on Monday on a 10-month mission expected to reveal previously unseen objects ranging from near-Earth asteroids to some of the most distant galaxies in the cosmos.

The Wide-field Infrared Survey Explorer, or WISE, was carried into a polar orbit 326 miles above Earth by a Delta II rocket that lifted off before dawn from Vandenberg Air Force Base in central California.

"All systems are looking good, and we are on our way to seeing the entire sky better than ever before," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena.

The $320 million instrument is designed to scan the entire heavens for the infrared radiation, or glow of heat, given off by objects that are too cold, too far away or too shrouded in dust to be seen by conventional visible-light telescopes.

Scientists say the spacecraft's detectors are about 500 times more sensitive than those of the last infrared sky survey in 1983, and are capable of producing photograph-quality images of the objects they find.

Among phenomena likely to be uncovered are large numbers of failed stars called brown dwarfs -- balls of gas many times smaller than the sun that lack sufficient mass to trigger their own internal stellar engines.

Optically invisible, brown dwarfs are thought to be more numerous than actual stars in the nearby universe. Some may reside even closer to Earth than the nearest known star, Proxima Centauri, about 4 light years away.

Closer to home, WISE is expected to find hundreds of previously uncharted asteroids and comets in the neighborhood of Earth's orbit, revealing more about the inventory of such "near-Earth objects" and their composition.

At the farthest reach of its gaze, WISE will be able to illuminate and peer through the dense haze that has obscured some of the most distant and powerful star clusters in the universe -- a class of objects called ultra-luminous galaxies.

Located 10 billion light years from Earth, these galaxies are believed to be super-incubators of new stars, shining with more than a trillion times the light of the sun, though most of that light is emitted in infrared.

Kansas scientists probe mysterious possible comet strikes on Earth

Brendan M. Lynch

University of Kansas
Mon, 14 Dec 2009 20:25 EST

An investigation by the University of Kansas' Adrian Melott and colleagues reveals a promising new method of detecting past comet strikes upon Earth and gauging their frequency

It's the stuff of a Hollywood disaster epic: A comet plunges from outer space into the Earth's atmosphere, splitting the sky with a devastating shock wave that flattens forests and shakes the countryside.

But this isn't a disaster movie plotline.

"Comet impacts might be much more frequent than we expect," said Adrian Melott, professor of physics and astronomy at the University of Kansas. "There's a lot of interest in the rate of impact events upon the Earth. We really don't know the rate very well because most craters end up being destroyed by erosion or the comets go into the ocean and we don't know that they're there. We really don't have a good handle on the rate of impacts on the Earth."

An investigation by Melott and colleagues reveals a promising new method of detecting past comet strikes upon Earth and gauging their frequency. The results will be unveiled at the American Geophysical Union's Fall Meeting, to be held Dec. 14-18 in San Francisco.

The research shows a potential signature of nitrate and ammonia that can be found in ice cores corresponding to suspected impacts. Although high nitrate levels previously have been tied to space impacts, scientists have never before seen atmospheric ammonia spikes as indicators of space impacts with our planet.

"Now we have a possible new marker for extraterrestrial events in ice," Melott said. "You don't just look for nitrates, you also look for ammonia."

Melott studied two possible cometary airbursts with Brian Thomas, assistant professor of physics and astronomy at Washburn University, Gisela Dreschhoff, KU adjunct associate professor of physics and astronomy, and Carey Johnson, KU professor of chemistry.

In June 1908, a puzzling explosion rocked central Siberia in Russia; it came to be known as the "Tunguska event." A later expedition found that 20 miles of trees had been knocked down and set alight by the blast. Today, scientists have coalesced around the idea that Tunguska's devastation was caused by a 100-foot asteroid that had entered Earth's atmosphere, causing an airburst.

Some 13,000 years earlier, an occurrence thought by some researchers to be an extraterrestrial impact set off cooler weather and large-scale extinctions in North America. The "Younger Dryas event," as it is known, coincided with the end of the prehistoric Clovis culture.

Melott and fellow researchers examined data from ice cores extracted in Greenland to compare atmospheric chemistry during the Tunguska and Younger Dryas events. In both instances, Melott's group found evidence that the Haber process - whereby a nitrogen fixation reaction produces ammonia - may have occurred on a large scale.

"A comet entering the atmosphere makes a big shock wave with high pressure - 6,000 times the pressure of air," said Melott. "It can be shown that under those conditions you can make ammonia. Plus the Tunguska comet, or some fragments of it, landed in a swamp. And any Younger Dryas comet presumably hit an ice sheet, or at least part of it did. So there should have been lots of water around for this Haber process to work. We think the simplest way to explain the signal in both objects is the Haber process. Comets hit the atmosphere in the presence of a lot of water and you get both nitrate and ammonia, which is what both ice cores show."

Melott cautions that the results are inconclusive because the ice cores are sampled at five-year intervals only, not sufficient resolution to pinpoint peaks of atmospheric nitrates and ammonia, which rapidly would have been dissipated by rains following a comet strike.

But the KU researcher contends that ammonia enhancement resulting from the Haber process could serve as a useful marker for detecting possible comet impacts. He encourages more sampling and analysis of ice cores to see where the nitrate-ammonia signal might line up with suspected cometary collisions with the Earth.

Such information could help humankind more accurately gauge the danger of a comet hitting the Earth in the future.

"There's a whole program to watch for near-Earth asteroids as they go around the sun repeatedly, and some of them have close brushes with the Earth," said Melott. "But comets are a whole different ball game. They don't do that circular thing. They come straight in from far, far out - and you don't see them coming until they push out a tail only a few years before they would enter the inner solar system. So we could be hit by a comet and only have a few years' warning - possibly not enough time to do anything about it."

Absence of Evidence for a Meteorite Impact Event 13,000 Years Ago

ScienceDaily

Mon, 14 Dec 2009 21:46 EST

An international team of scientists led by researchers at the University of Hawaii at Manoa has found no evidence supporting an extraterrestrial impact event at the onset of the Younger Dryas approximately 13,000 years ago.

The Younger Dryas is an abrupt cooling event in Earth's history. It coincided with the extinction of many large mammals including the woolly mammoth, the saber toothed jaguar and many sloths. This cooling period is generally considered to be the result of the complex global climate system, possibly spurred on by a reduction or slowdown of the thermohaline circulation in North America. This paradigm was challenged two years ago by a group of researchers that reported finding high iridium concentrations in terrestrial sediments dated during this time period, which led them to theorise that an impact event was instead the instigator of this climate shift.

A team led by François Paquay, a Doctoral graduate student in the Department of Geology and Geophysics at the University of Hawaii at Manoa (UHM) decided to also investigate this theory, to add more evidence to what they considered a conceptually appealing theory. However, not only were they unable to replicate the results found by the other researchers, but additional lines of evidence failed to support an impact theory for the onset of the Younger Dryas.

Their results will be published in the December 7th early online edition of the Proceedings of the National Academy of Sciences.

The idea that an impact event may have been the instigator for this cooling period was appealing because of several alleged impact markers, especially the high iridium concentrations that the previous team reported. However, it is difficult for proponents of this theory to explain why no impact crater of this age is known. "There is a black mat layer across North America which is correlated to the Younger Dryas climatic shift seen in Greenland ice cores dated at 13,000 years ago by radio carbon," explains Paquay. "Initially I thought this type of layer could be associated with an impact event because concentration in the proxies of widespread wildfires are sky high. That plus very high levels of iridium (which is one indicator used to indicate extraterrestrial impact events). So the theory was conceptually appealing, but because of the missing impact site, the idea of one or multiple airburst arose."

To corroborate the theory, Paquay and his colleagues decided to take a three-pronged approach. The first was to replicate the original researchers data, the second step was to look for other tracers, specifically osmium isotopes, of extraterrestrial matter in those rocks, and the third step was to look for these concentrations in other settings. "Because there are so many aspects to the impact theory, we decided to just focus on geochemical evidence that was associated with it, like the concentration of iridium and other platinum group elements, and the osmium isotopes," says Paquay. "We also decided to look in very high resolution sediment cores across North America, and yet we could find nothing in our data to support their theory."

The team includes American, Belgian and Canadian researchers. Analysis of the sediments was done both at UHM and in Belgium, using the same sediments from the same interval and indepedently did the analysis work and got similar results. Both the marine and terrestrial sediment records do not indicate that an impact event was the trigger for the transition into the Younger Dryas cold period. "The marine and terrestrial record both complement each other to support this finding," concludes Paquay. "That's what makes the beauty of this study."

This project was supported by the Geological Society of America and the National Science Foundation. Sediment samples were provided by the Integrated Ocean Drilling Program.

The other authors from this paper are Greg Ravizza (also from UHM), Steven Goderis and Philippe Claeys from Vrije Universiteit Brussel, Frank Vanhaeck from the Universiteit Ghent, Matthew Boyd from Lakehead University, Todd A. Surovell from the University of Wyoming at Laramie, and Vance T. Holliday and C. Vance Haynes, Jr. from the University of Arizona at Tucson.

This research will be presented at the American Geophysical Union Fall 2009 Meeting in San Francisco. Wednesday December 16th, 2:52 PM -- 3:04 PM, Room 2006 Moscone West

Journal Reference:

François S. Paquay, Greg Ravizza, Steven Goderis, Philippe Claeys, Steven Goderis, Frank Vanhaeck, Matthew Boyd, Todd A. Surovell, Vance T. Holliday, C. Vance Haynes, Jr. "Absence of geochemical evidence for an impact event at the Bølling - Allerød/Younger Dryas transition." Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0908874106

England: Single green light seen crossing the sky

UK UFO Sightings

Tue, 15 Dec 2009 13:32 EST

Posted: December 14, 2009

Location of Sighting: Redditch, Worcestershire
Date of Sighting: 11th December 2009
Time: 2315

Witness Statement: From my location just North of the town centre in Redditch, I saw a single green light crossing the sky from East to West at an angle of elevation of about 30-40 degrees, and over Redditch town centre (although it was impossible to tell how far away it was).

I would estimate the light to have been 10-15% the apparent diameter of the Sun, and wasa vivid green reminiscent of a flare, but not as bright.

I appreciate that that direction of travel would have made the starboard navigation light of an aircraft a possibility, but it was far brighter than a nav light, and it's size as viewed would have put the aircraft only a few hundred metres away. There was no sound whatsoever.

Redditch is now within the Controlled Airspace surrounding Birmingham, but Birmingham Zone air traffic control was not talking to any aircraft in the vicinity at the time, and nothing showed up on my Virtual Radar system.

Alleged Meteorite Fall Causes Alarm in Santiago, Chile

Tue, 15 Dec 2009 01:20 EST

Terra

A long white trail that appeared to be the fall of a meteorite was seen in the morning over the mountains.

However, after several inquiries the meteorite hypothesis was dismissed against the hipothesis of a meteorological effect.

According to sources of the Bureau of Aeronautics, it was an aircraft that was headed for Argentina and that, by the effects of temperature difference and contact of the turbine with the cooler air, generated a bright trail that remained in the sky.

Esteban Hermosilla captured this phenomenon in the morning when droving to work from Lo Barnechea to Huechuraba.

"I was going down the Costanera highway and you could clearly see the marked trail, so I took a picture with my cellphone. I didn't know what it was, I was astonished, I thought it was a plane but it was very strange"said Esteban Hermosilla.

See video here (in Spanish)

Earthquake follows Nebraska fireball

Spaceweather.com
Thu, 17 Dec 2009 08:02 EST

"At 9 p.m. Central Time on Dec. 16th, a very bright meteor lit up the completely overcast sky like lightning in southeast Nebraska," reports Trooper Jerry Chab of the Nebraska State Patrol. "It flashed for approximately 2 seconds and was followed by ground shaking, which prompted many calls by the public to law enforcement in a three county wide area." The USGS says there was a magnitude 3.5 earthquake near Auburn, Nebraska, at 8:53 pm Wednesday night, about the same time and place as the fireball. Coincidence? Readers in Nebraska with photos or eyewitness accounts are encouraged to submit a report.

US: Sonic boom-like noise heard by many last night

WGMD 92.7 News Radio

Thu, 17 Dec 2009 11:50 EST

A sonic boom like sound heard by many late last night is something that has happened before, according to State Police. They tell us that is what it probably is. They tell us there was nothing reported to them last night as far as an explosion or anything suspicious. Delaware's Dover Air Force Base has no information regarding any aircraft from their base that the noise may have been related to.

US: Mysterious booms questioned

Foss Farrar

The Arkansas city Traveler
Wed, 16 Dec 2009 13:30 EST

Stop. Hey, what's that sound?

Several Arkansas City area residents reported hearing explosion-type sounds or sonic booms recently. But authorities can't seem to pinpoint the source of the sounds.

Elmer Morris, a World War II veteran, today said he heard the booms two or three times on Monday and several more times Tuesday. The booms were heard during daylight hours, he said.

Morris said the sounds are very similar to sonic booms he heard while in the military and on the West Coast.

He didn't hear the mysterious sounds today, he said late this morning.

"I've seen jets flying high, leaving a vapor trail," said Morris, who lives in Crestwood.

"But no booms today."

If jets fly low and break the sound barrier, windows rattle and sometimes crack, he added. They aren't supposed to do that.

Undersheriff Bill Mueller said he also heard reports of the sounds from a few individuals, including his wife, over the past few days.

But the source of the sounds has not been located.

"I'll have the deputies be on the alert," he said.

Mueller and two officials at Strother Field said they are skeptical that the sounds are sonic booms.

Cosmic Firework Lights Up the Sky Above the Mojave Desert

Fri, 18 Dec 2009 15:00 EST

Daily Mail

A huge meteor hurtles to Earth during the annual Geminid meteor shower. The picture was taken from the Mojave Desert area near Victorville

This incredible picture shows a huge meteor hurtling to Earth during the annual Geminid meteor shower.

Astro-photogrpaher Wally Pacholk captured this amazing shot in the Mojave Desert area near Victorville under a dark and almost clear sky.

The annual cosmic fireworks have been growing in intensity in recent decades with up to 160 meteors visible per hour under optimal conditions. They travel across the sky at about 22miles per second and are fairly easy to spot.

The Geminids are caused by the Earth crossing the debris-strewn path of the extinct comet 3200 Phaethon. The first recorded sightings were in 1862 in England and the U.S. In these early days only 14 meteors were recorded per hour.

Viewing conditions were particularly good this year because it peaked on Monday morning two days before a new Moon.

They are best viewed from the Northern Hemisphere although you can see up to 20 meteors per hour near the horizon in the Southern Hemisphere.

Fireball: Curious Events In Nebraska: Dec. 16, 2009

Fri, 18 Dec 2009 05:51 EST

SpaceWeather

Earthquakes don't rock Nebraska very often. In fact, seismically speaking, it is one of the quietest places in North America. Nevertheless, on Dec. 16th at 8:54 pm CST, USGS seismographs detected a magnitude 3.5 temblor centered near Auburn, Nebraska:

"It sounded like those loud grain haulers that drive by, but about five times louder," reports Laurie Riley, who lives near the epicenter. "The whole house shook. My kids came running down stairs - they were scared. It even moved my car, [which was parked outside on icy ground]."

And then the really curious thing happened.

Minutes after the quake, around 9 pm CST, lightning-like flashes lit up the skies around the area of the quake. Telephones in police departments and TV stations rang with reports of bright lights, loud rumbles and shaking ground. Sky watchers, not only in southeastern Nebraska, but also in neighboring Oklahoma, Missouri and Kansas, saw a "bright fireball" with "green streamers" moving from northwest to southeast.

Could these events be connected? Nebraska State Trooper Jerry Chab, an experienced amateur astronomer who witnessed the lights and was one of the first to report them, says no. "I think we have the most cosmic of coincidences: A bright [meteoritic] fireball around the same time as an earthquake." Indeed, eyewitness descriptions of the fireball are consistent with a meteoroid disintegrating in the atmosphere. On the other hand, several readers have pointed out scientific studies that associate lightning-like phenomena (including ball lightning) with earthquakes: #1, #2, #3. The fireball, they suggest, might have been a rare manifestation of "earthquake lightning."

Eyewitness Fireball-Quake Reports

Earthquakes in Nebraska are rare, so what are the odds of one happening within minutes of a meteoritic fireball? This might be a cosmic coincidence. Or there could be some yet-to-be-explained linkage between the events. Readers with photos or eyewitness reports are invited to submit them here.

Summary: The nature of this event is uncertain--indeed, it might be more than one event. Around 9 pm on Dec. 16th, sky watchers in southeast Nebraska saw a brilliant fireball streak across the sky. It was so bright that observers with overcast skies saw it shining through clouds. Telephones in news stations and police departments rang with reports of bright lights, loud sounds, and ground shaking. Minutes earlier, around 8:53 pm CST, the USGS says there was a magnitude 3.5 earthquake in southeastern Nebraska.

Eyewitness Accounts:

Location: 5 miles NW of Pawnee City, Nebraska
Comments: Nebraska State Trooper Jerry Chab: "At 2100 CST tonight a very bright meteor lit up the entire completely overcast sky like lightning in southeast Nebraska. It flashed for approximately 1.5-2 seconds and was followed by sonic booms and ground shaking which prompted many calls by the public to law enforcement in a three County wide area."

"I was approximately 5 miles NW of Pawnee City, Ne. when I observed the flashes," Chab continues. "It was a very bright one, the sky dimmed a bit and it was followed by another bright flash. Between the two bright flashes the sky never completely dimmed. Again, this all occurred within 1.5-2 seconds. I talked to a truck driver who was approx. 8 miles straight East of me who saw the same thing. A local Deputy was about 16 miles ENE of me and also saw it. The first 911 call came at 2201. The calls were about explosions AND earthquakes. One individual call mentioned 'two' explosions. I attributed the calls to sonic booms."

"If the Earthquake is confirmed, as it appears to be, I think we have the most cosmic of coincidences: A large fireball around the same time of an Earthquake. I am simply amazed!!"

Location: Nebraska City, Nebraska (near Auburn, Nebraska)
Comments: Laurie Riley: "It sounded like the loud grain haulers that go by but about 5 times louder. The whole house shook. The kids came running down stairs - they were scared. The only thing I noticed last night is my vehicle was moved - since it's been snowing and ice out, I park backwards and park with two tires on my sidewalk for traction and after the quake, it shook my vehicle so the back tire slide off the sidewalk and the front tire was almost off. It lasted about 5 seconds or so. Very loud rumble."

Location: Warren County, Missouri
Comments: Doug Kniffen: "My daughter and I saw the fireball from east central Missouri (Warren County). 9:05pm on my wristwatch (set to WWV). The fireball appeared about magnitude -6, with distinctly green streamers outlining the tail. Certainly an impressive sight, sure wish I had a picture. Very low apparent altitude, would have missed it if the trees hadn't dropped their leaves. Told my daughter that there was a good chance of fresh meterorites in Nebraska. Nice to know that my estimate of a fall zone was close."

Location: Hastings, Nebraska
Comments: Rich Cartier: "Sitting in a well-lit living room watching TV, I noticed out the east-facing living room window a bright fireball heading from northwest to southeast. It lasted about 2 seconds with a bright flash at the end. It was remarkable, since it was overcast, and I was in a bright room, yet it still caught my eye."

Location: between Wichita and Andover, Kansas
Comments: Alan Howarter: "At about 9:06 pm on Wednesday, December 16, 2009 I was driving North and witnessed what appeared to be a very bright meteor toward the northeast that lit up for a couple of seconds."

Location: Oklahoma City, Oklahoma
Comments: Rick Foster: "I saw a huge green fireball at 9:03 pm from Oklahoma City almost due north. Very low on horizon. Looked like it was moving NW to SE. I was in my truck driving north on I-35. It was very large, green with orange sparks and very short tail."

Green meteor lights up night sky

The Telegraph

Fri, 18 Dec 2009 15:24 EST

© Barcroft
A huge meteor hurtling to earth during the annual Geminid meteor shower, taken from the Mojave Desert area near Victorville

A green meteor was seen over the Mojave Desert in California as part of the annual Geminid meteor shower.

Astro-photogrpaher Wally Pacholka captured the annual cosmic fireworks show under dark and clear skies on Monday.

The meteor shower has been growing in intensity in recent decades and was enhanced this year by it falling in a nearly moonless week.

Featuring as many as 140 shooting stars every hour, the Geminid show took place between Sunday evening and Monday morning.

Taking 1522 photographs and capturing 48 meteors, Mr Pacholka was able to get this amazing image.

"The Gemini shower in my opinion is always the best meteor shower of the year and this one was the best I had ever seen with activity of at least 150 per hour near peak time", he said.

"A meteor this monster size is extremely rare to see, never mind photograph.

"It has to be one of the brightest meteor photographs on record."

The Geminids are slow meteors that create beautiful long arcs across the sky with many lasting more than a second.

The shower's radiant the point in the sky from which the meteors appear to originate is the Gemini constellation, giving the event its name.

The Geminids have been historically overlooked by stargazers, simply because of their timing so close to the busy holiday season and during frezzing winter nights, astronomers say.

China: Fireball in Beijing

Cui Xiaohuo

China Daily
Mon, 21 Dec 2009 09:43 EST

The search continues for a full moon-bright meteoroid likely to have landed in west suburban Beijing on Wednesday in what astronomers said could lead to one of the biggest discoveries in Beijing this year.

Witnesses in Beijing and nearby Tianjin recorded a clearly visible fireball-like meteorite descending near the west horizon of Beijing at 10:23 pm on Dec 16.

The surveillance camera from the planetarium taped a 2-second footage of the fall phenomena, in which a bright shooting star, carrying a visible tail, flew towards the east and exploded into greater brightness before disappearing on the horizon.

"We were at Jianxiangqiao Bridge when driving west-bound on the North Fourth Ring Road when we caught sight of the brightness moving to the southeast," Li Xin, a researcher with the Beijing Planetarium, wrote on the organization's online forum before posting the surveillance video right after the witness.

"The brightness of the meteor was close to a full moon," he wrote. "If this meteorite can be recovered, it can become one of the biggest discoveries in Beijing."

Other residents in Beijing also reported witnesses of the "fireball-like meteorite" to the planetarium.

"Wow, what was it that I saw," wrote one Beijing-based blogger on the popular portal douban.com, only 12 minutes after the fall phenomena occurred.

"I was at Chaoyangmen on the East Second Ring Road and I just saw a bright green ball of light moving to the south. There were no noises and everything seemed fine outside my car," wrote the blogger, who named himself "awkward uncle".

But the online witnesses did not draw much serious attention before verified by the astronomy authority.

"You were really awkward, dear uncle. That was Optimus Prime," a comment from reader "XY" followed. Other readers exclaimed the entire witness sounded "very Sci-Fi".

Astronomers from the Beijing Planetarium said the witness was telling the truth and researchers said they have already reported the witness to the International Meteor Organization as the latest visual meteor on Earth.

Li also estimated the location of the landing to be about 40 km west of downtown Beijing, while Zhu Jin, director of the planetarium, put the estimation at between 100 and 200 km from central Beijing. The Baihuashan mountainous area at the border of Beijing and nearby Hebei province was noted to be the most possible location, Zhu said.

Scientists have launched a campaign online and through TV to collect witnesses and accounts. Residents in west Beijing are encouraged to contribute.

But it was unknown what the debris of the meteor would be like, experts said. If recovered, the discovery will be viewed as a "fall" according to international practice.

The Beijing Planetarium has never collected any meteorite from past meteors in Beijing.

As of mid-2006, there have been approximately 1,050 witnessed falls producing specimens for the world's collections.

"The witness was lucky. No techniques were involved whatsoever," Li said.

Flame-Shooting UFO (Meteor?) Spotted Near A47

Lynn News

Tue, 22 Dec 2009 11:53 EST

A motorist travelling towards Lynn was amazed when he saw a flame-spewing UFO shoot across the sky and then disappear before his eyes.

Jimmy Greenwood (45) is convinced the flying object, about the size of a football, was a meteorite, but is appealing to Lynn News readers to help him find out for sure.

Mr Greenwood was driving along the A47, just outside of Wisbech, at around 12:45pm on Saturday when he saw a bright white light travel across the sky with flames coming out behind it.

He said: "I was on my way to see my daughter. It was snowing and I was driving around 35 to 40mph. I saw this really bright light over the fields to my right for about two to three seconds and then it just burned away. It looked like a firework rocket and was moving really quickly.

"The people in the car behind definitely saw it too, they were pointing towards it and you couldn't really miss it. I've never really seen anything like it and I think it was definitely a meteorite."

Mr Greenwood, of Townley Close, Upwell, immediately phoned his daughter and brother to tell them what he saw.

"I've rung lots of people, but they just laughed!" he added.

UK: Daylight fireball reported

Asha Mehta

Peterborough Today
Wed, 23 Dec 2009 16:17 EST

Sightings of a rare daylight "fireball" - thought to be a meteor - was seen flashing over the Wisbech skies.

A meteor which has passed through Earth's atmosphere is known as a meteorite, and experts say pieces of the space rock could now be scattered across a Fenland field.

It was spotted by Jimmy Greenwood, who was driving along the A47 just outside Wisbech at about 1.15pm on Saturday. The 45-year-old, from Upwell, said: "I've never seen anything like it. It was about four houses high and burning white. It went straight across quickly, into a field and disappeared. It had a vapour trail. It was unbelievable."

Dr John Mason, acting director of the British Astronomical Association's meteor section, said: "Such sightings are rare since few fireballs are bright enough to be visible in broad daylight. Sightings have so far been received from observers in South Yorkshire, Lincolnshire and Norfolk, but it's likely that the event would have been visible across most of the East Midlands and Eastern England."

Chairman of the Peterborough Astronomical Society Martin Hall said: "It's exciting, especially as it might have landed."

The Society of Popular Astrology's (SPA) internet forum was later buzzing with people's accounts of the sighting.

Assistant meteor director at the SPA David Entwistle, said: "What people have seen is a bright, fast- moving light in the sky - a meteor. It is very unusual to have a daylight meteor. If we get a collection of reports from people, we can try to triangulate the path of the meteor and if it landed, work out where."

Mr Entwistle is urging anyone who witnessed the fireball to e-mail the time of the event, the altitude, location and its appearance to either len.entwisle@btopenworld.com or radiometeor@popastro.com

Maryland, US: Strange Fiery Object Found On Beach

Shawn J. Soper

Maryland Coast Dispatch
Fri, 25 Dec 2009 06:32 EST

Ocean City - A mysterious, glowing hot object fell from the sky and landed on the beach in Ocean City last week, but it remains uncertain this week just what it is and from where it came.

Early last Tuesday morning, an Ocean City cab driver was walking down the Boardwalk in the area of 22nd Street when he saw a bright glowing object fall from the sky from north to south and land on the beach roughly 20 yards away from him. Classic Cab Company driver Derrick Miller typically drops his taxi back off at company headquarters on 26th Street after his shift and walks down the Boardwalk to his home in the downtown area.

Over the years, he has established a relationship with a resident wild fox that inhabits the area around 22nd Street in front of the Grand Hotel and often brings food to the animal. Early last Tuesday morning, Miller was following his normal routine when he saw a bright light flash across the sky from the north with the glowing object landing on the beach about 20 yards away.

"I was doing my usual thing and I was on the beach right in front of the Grand when I saw what looked at first like a shooting star," he said. "It crashed into the sand about 20 yards away from me. When I checked it out, it had made a hole in the sand about a foot and a half wide and about six inches deep. Whatever it was, it was glowing red hot with sparks and fire coming from some of the holes in it."

Miller said he examined the object closely, but could not handle it because of the heat. Instead, he buried it in the sand and marked the location with a stick. He returned about five or six hours later and recovered the object, which was still warm to the touch, but cool enough to pick up and handle.

The unknown oblong object is about an inch-and-a-half long on its longest side and an inch or so wide. Its shape is irregular and appears to contain different types of material. It is covered with small holes around the outside that appear to be fissures of some sort. Weighed this week at the Classic Cab warehouse, it came it at exactly 20 grams.

It is uncertain just what the object is and where it came from, but it fell from the sky during one of the most celebrated astronomical events in the northern hemisphere this year, lending credence to the working theory that is possibly a meteorite or other kind of space debris. According to NASA officials, the Geminid meteor shower arched its way across the northern hemisphere sky from Dec. 6-18, providing one of the most visible astronomical events of the year.

According to NASA, the Geminid meteor shower reached its peak on Dec. 13-14, which puts last week's discovery on the beach in Ocean City right in the window of the most activity in the area. While he could not be reached for comment or possible identification of the object, Bill Cooke of NASA's Meteoroid Environment Office confirmed the Geminid meteor shower provided fireworks over the mid-Atlantic area last week.

"It's the Geminid meteor shower and it should have peaked on Dec. 13th and 14th under ideal viewing conditions," he said. "The Geminids are strong and getting stronger each year."

Miller said in the days before and after his discovery of the object on the beach, he noticed an increase in the number of shooting stars observed in the area, particularly on the beach at night or in darker areas such as Ocean Pines while he was driving his cab. He also said many of his fares had pointed out the phenomenon.

According to NASA, Geminids are pieces of debris from a strange object known as 3200 Phaeton. Long thought to be an asteroid, Phaeton is now classified as an extinct comet. According to NASA, "it is basically the rocky skeleton of a comet that lost its ice after too many close encounters with the sun," and "Earth runs into a stream of debris from 3200 Phaeton every year in mid-December, causing meteors to fly from the constellation Gemini."

Of course, it remains uncertain just what the object Miller discovered on the beach last week is, but the presence of the Geminid meteor shower during the time it was found suggests it could be an object from outer space, possibly a meteorite.

A meteorite is defined by NASA as a natural object originating in outer space that survives a trip through the Earth's atmosphere and lands on the ground. Most meteorites come from small astronomical objects called meteoroids, but they are sometimes produced by impacts of asteroids. According to NASA, meteorites that are recovered after being observed as they transited through the atmosphere or impacted the Earth are called "falls." All other meteorites are known as "finds."

According to NASA, most meteoroids disintegrate when entering the Earth's atmosphere. However, an estimated 500 meteorites ranging in size from marbles to basketballs or larger do reach the surface each year. Few meteorites are large enough to create impact craters. Instead, they typically arrive at the surface at their terminal velocity and, at most, create a small pit, according to NASA.

Reality matches Dreaming story

Deborah Smith

Sydney Morning Herald
Sun, 27 Dec 2009 18:01 EST

An Aboriginal dreaming story about a star crashing to Earth with a noise like thunder has led to the discovery of an ancient meteorite crater in central Australia.

A Sydney astronomer, Duane Hamacher, found the bowl-shaped crater in Palm Valley, about 130 kilometres south-west of Alice Springs, by searching on Google Earth.

He was inspired to look there after learning of traditional stories told by the local Arrernte people about a star that had fallen into a waterhole called Puka in the valley.

Mr Hamacher, a PhD candidate at Macquarie University, said that reality matching the Dreaming story could be a case of pure chance.

''But if so, it's an incredible coincidence,'' he said.

He is part of a team, led by a CSIRO astronomer, Ray Norris, that is exploring the possibility that Aborigines were the world's first astronomers.

Traditional Aboriginal wisdom about the heavens was impressive, Mr Hamacher said.

''It is impossible to survive on a continent like this for 50,000 years and not have an intimate knowledge of the natural world around you, including the night sky,'' he said.

He searched historical records for Aboriginal stories with references to comets, meteors and cosmic impacts, and looked for matching astronomical events.

The Palm Valley crater, which the team proposes to name Puka, was probably formed millions of years ago, so people could not have witnessed this impact.

''But perhaps the Arrernte knew rocks fell out of the sky and maybe they deduced that a large rock caused the big bowl-shaped crater,'' he said.

Another Arrernte Dreaming about a large impact crater called Gosse's Bluff, which formed about 142 million years ago, ''closely parallels the scientific explanation'', he said.

The crater, about 175 kilometres west of Alice Springs, is known as Tnorala and considered a sacred place by the Western Arrernte people, who say it was formed when a group of sky-women were dancing as stars in the Milky Way.

One woman who grew tired placed her baby in a wooden basket, but it fell to Earth, ''forcing the rocks upward'' into the crater's circular mountain range.

After spotting the Palm Valley crater on the internet, Mr Hamacher visited the site with two Macquarie University geophysicists, Craig O'Neill and Andrew Buchel, and an astrophysicist, Tui Britton.

''We found evidence of shocked quartz, which is only produced when there is a substantial impact,'' Mr Hamacher said.

They also determined that the structure was bowl shaped under the surface, which could not be explained by erosion.

November 2009

2009-12-14T21:42:00.010Z

Comet Caesar - Dark Comet in 2012?

Robert Bast

Survive 2012.com
Mon, 02 Nov 2009 18:50 EST

When considering what might cause us grief in 2012, few if any researchers consider the start of the Mayan Long Count calendar to have any importance. This is surprising, because the reason for the calendar beginning on August 11 3114BC might contain clues about 2012 itself. After all, the Mayan culture did not exist 5,000 years ago, so either they randomly chose an ancient date on a whim, or an earlier civilization was behind the calendar, and they knew something important occurred on that date.

What could happen in 3114BC, and also in 2012AD? No civilization has lasted that long, so they are unlikely to be man-made events. Any natural events that occur so infrequently on Earth are virtually impossible to predict (volcanic eruptions for example). So that leaves us with astronomical events. The astrology of the pair of dates has been well studied, so we can rule out alignments of the stars and planets. That leaves the Sun, which we barely understand today, and comets. Is there a comet with a periodicity of 5000 years, due to return in 2012? Without any evidence from 3114BC it is impossible to say. Given that we are now near the end of the Mayan 5th age, could their calendar be designed to cover five orbits of a comet? And end catastrophically in 2012?

Most people have not heard of Comet Caesar (it doesn't even have a Wikipedia entry), and hopefully this will remain so. However, if we are to suffer a terrible tragedy in 2012, it is currently my leading candidate, and the purpose of this article is to explain why.

Comet Caesar was the most famous comet of its day, and one of the brightest ever witnessed. It was visible during an annual Roman festival held in 44BC, shortly after Julius Caesar's death. The following quotes are from The Greatest Comets in History: Broom Stars and Celestial Scimitars by David Seargent:

This was the comet that blazed in the skies of Rome following the assassination of Julius Caesar and which became immortalized by the Romans on the reverse of a coin bearing a portrait of Augustus struck in honor of the great Julius.

...According to Pliny, Octavian wrote that "On the very days of my games, a comet was visible over the course of seven days, in the northern region of the heavens. It rose at about the eleventh hour of the day and was bright and plainly seen from all lands".

...In the fourth century of our era, Servius presented an account that had the comet visible for 3 days and visible at midday and during the daytime.

Comet Caesar is a parabolic comet - a comet that returns less frequently than every 200 years. Most parabolic comets have orbits significantly longer than 200 years, and very few have ever been observed to make a complete orbit. Astronomers expect 50 percent of parabolic comets will receive gravitational nudges that cause them to never orbit the Sun again. Those that remain in orbit should be slowed with each passage, eventually becoming intermediate or short-period comets. Therefore we either never see them again, or they take so long to return that we don't know which, if any, have historical records they match up with.

In my search for the most likely 2012 culprit, I have constantly asked myself, could the ancients have predicted this? Asteroids and comets are definitely predictable in a broad sense, and all that it takes is observation and mathematics. Such calculations are not easy. They require recalculating the orbit for every day of every year, according to where the object is then located, and how the planets are affecting its course. If ancient astronomers had considered the period of a comet or asteroid to be fixed, rather than varying due to the gravitational influences of planets, then there may have been inaccuracies in any 2012 prediction they made. However the daily recalculations were certainly not impossible in ancient times.

Predictability of Comets

Perhaps the most famous comet, even today, is Halley's Comet. Edmond Halley - as well as a team of French mathematicians - predicted the return of this comet, not just from knowing the dates of its past visits, but by calculating the gravitational effects of planets like Saturn and Jupiter. They did this by hand.

A single line in the Talmud suggests that 1st century Jewish astronomers were also aware of the periodicity of Halley's Comet:

"a star which appears once in seventy years that makes the captains of the ships err"

To go from calculating the return of a comet, to having knowledge that it will probably strike Earth, is a major leap. Although that is not to say they weren't merely predicting the return of a spectacular comet, let's investigate the possibility that an ancient culture was capable of predicting the actual impact of a comet in 2012.

First of all, for this hypothesis to have any validity, the comet must be a long period one; that is, it must pass our planet less frequently than once every 200 years. More frequent comets would be well known by modern astronomers, and would most likely have their future orbits determined.

According to Wikipedia, there are just 40 known comets with a periodicy greater than 200 years (or non-periodic comets). Of these, 38 have been observed since 1577AD. The only prior dates were 1106AD and 44BC. To me this suggests that a great many earlier observations would have been made, we just don't have evidence of such. The Great Comet of 1106AD was seen from Europe to Japan. A Welsh text said of it:

In that year there was seen a star wonderful to behold, throwing out behind it a beam of light of the thickness of a pillar in size and of exceeding brightness.

Were we to have detailed records of comets from more historical times, we might have a similar description with which we could determine the periodicity of the 1106 comet. Without this, we have nothing to base its return on - could be tomorrow, could be never.

You could say the same about Comet Caesar, the aforementioned earliest recorded comet of 44BC. Without another record of it, we cannot determine when it will return next. While there may not be any surviving record of a prior passage, perhaps we can make an implication from the Long Count calendar. If the end of the calendar is actually the date a comet will strike Earth, what is the most logical reason for the start date?

If, and this is obviously pure speculation, it had been observed in 3114BC, and again in 44BC, could it be returning once again in 2012? With a precise periodicity of 1025.2 years we get the following sequence of dates:

3114BC - start of the Long Count calendar

2089BC - 2104/2105 is when the Great Flood occurred according to the Hebrew Calendar

1064BC - 1077 was the end of the Egyptian New Kingdom, marking the beginning of Egypt's decline

39BC - Comet Caesar was witnessed in 44BC

987AD - Dark Ages

2012AD - end of the Long Count calendar

Is 39BC close enough to 44BC? In 1758 the French astronomers who calculated the return of Halley's Comet determined that the gravitational effects of Saturn and Jupiter would make a difference of 618 days to its existing orbit, or almost 2 years. Is a difference of 5 years within 5 orbits outside the realms of possibility?

Variable Periodicity of Comets

When Comet Hyakutake was discovered in 1996, astronomers determined that on the way in to our solar system it had an estimated periodicy of 17,000 years, yet after having its orbit disturbed by the largest planets, its new course meant it would take between 72,000 and 114,000 years to return.

When 23P/Brorsen-Metcalf was first discovered it was closest to Earth in August 1847. After completing its orbit it was back in that approximate spot in October 1919, and again in August 1989. The two observed periods were 72 years and 70 years. That's roughly a 3% deviation between 2 orbits.

The periodicy of a comet can vary from a little, to a lot, to so much we never see it again. It is entirely possible that Comet Caesar was seen the very same years as the Great Flood, the end of the Eygptian New Kingdom, the start of the Long Count calender - and will return in 2012.

Where are the records?

...they were either not observed or were observed and recovered by illiterate, uneducated peasants. It was quite unthinkable that the sophisticated urban theologian of A.D. 1000... should take seriously the allegations of such rabble that stones fell from the sky.

...Modern astronomers seeking accounts of ancient astronomical events ...find the records of medieval Europe sparse at best.

To explain the absence of records for Comet Caesar prior to 44BC is easy - lost in the annals of history that never made it. But what of 987AD? Could it really go from observed in 44BC, to not observed at all? Or has the record from 987AD +/-3 years, just disappeared?

The former possibility is covered by the concept of dark comets, described below. To answer the latter possibility, 987 was in the Dark Ages, renowned for a lack of records. In fact so lacking that some researchers have speculated that the era never existed at all!

Halley's Comet was observed in 837 according to records from Japan, China, and Germany. The next observation was in 912, and was recorded in the Annals of Ulster, like this: "A dark and rainy year. A comet appeared". There is no specific record of its return in 990, and was next spotted in 1066, where it was recorded as having an influence on the Battle of Hastings.

The only mention of a comet circa 987AD (when I approximately hypothesize Comet Caesar would have returned) is indirect, and attributed to Eilmer of Malmesbury, a Benedictine monk:

You've come, have you? - You've come, you source of tears to many mothers. It is long since I saw you; but as I see you now you are much more terrible, for I see you brandishing the downfall of my country

He described this appearance in 1066. Because the previous passage of Halley's Comet would have been in 990AD, and he was an "old man" in 1066, it is believed that he could have seen the comet when he was 5 years old, and have would been 76 years old in 1066 when he was quoted. But what if he was just a few years older in 1066, and was actually recalling a comet he witnessed in 987AD? Could he have seen the most recent passing of Comet Caesar, and not Halley's Comet, in the closing years of the tenth century?

Taking a different angle, if there is no specific record of Halley's Comet in 990AD, it fits that a return of Comet Caesar circa 987AD also avoided any record that survives to this day.

For some, a simple lack of record will suffice, and the hypothesis is feasible. For the others, I will describe a mechanism from which the comet rapidly loses visibility.

Dark Comets

There's only one difference between dark comets and regular comets - we won't see the approach of the dark comet.

In early 2009 many news articles reported the findings of British astronomers Bill Napier (Cardiff University) and David Asher (Armagh Observatory), and reading them sent a shiver down my spine, prompting me to research the possibilities further.

"There is a case to be made that dark, dormant comets are a significant but largely unseen hazard," says Napier.

...periodic comet showers appear to correlate with the dates of ancient impact craters found on Earth, which would suggest that most impactors in the past were comets, not asteroids.

Now Napier and Asher warn that some of these comets may still be zipping around the solar system. Other observations support their case. The rate that bright comets enter the solar system implies there should be around 3000 of them buzzing around, and yet only 25 are known.

Until now it was commonly accepted that more than 90% of meteors and comets that could cause us harm were known and tracked by astronomers and government agencies. That thousands of comets that are potentially heading straight for us are not known or tracked is rather frightening. How can a comet become dark?

The science is actually quite easy to understand. Comets start out with ice on their surface. Every time they orbit around the Sun, the heat melts some ice. Eventually there is no ice left. And the only way we can easily see comets is from light reflecting off the ice.

In 1983, Comet IRAS-Araki-Alcock passed by Earth at a distance of 5 million kilometres, the closest known pass by any known comet for 200 years. It was spotted only two weeks ahead of its closest approach. "It had only 1 per cent of its surface active," says Napier. Comet Borrelly, visited by NASA's Deep Space 1 probe in 2001, was found to have extremely dark patches over much of its surface.

Clark Chapman, from the Southwest Research Institute in Boulder, Colorado, is not so concerned, saying that the dark comets 'would absorb sunlight very well' and therefore should be possible to detect from the heat they would emit. I'm not qualified to judge this statement, but from a layman's point of view, I would think a handheld mirror reflecting the sun's light from a mile away is far more easily seen than a slab of rock that is so hot you could fry an egg on it.

Here are a couple of examples of lost comets. One of the reasons they are no longer observed could be that they have lost their luminosity.

18D/Perrine-Mrkos - seen in 1896 and 1909, then 1955, then 1969, and not since.

5D/Brorsen - first spotted in 1846, last seen in 1879. With an orbital period of 5.5 years. Has been as close as 0.52 AU to Earth, and as far as 1.5AU. Japanese astronomers hoped to spot it in 1976, but failed.

The orbital period of 5D/Brorsen suggests it could be passing by in 2012, if it is still on course. There is even a possible case of a dark comet harming us (in a roundabout way) in recent times. Paul Wiegert of the University of Western Ontario has determined that the dark comet D/1895 Q1 (Swift) collided with NASA's Mariner 4 Mars probe in 1967. Given that the comet was only ever observed in 1895/1896, there is not enough data to be absolutely certain, but something took out the probe, and a dark comet is the leading candidate.

Many lost comets could be coming close to Earth in 2012, but without recent observations, there is no way of accurately calculating their passage.

A long period comet would be the best candidate for a 2012 culprit for two reasons:

an ancient civilization may have tracked comets for much longer than our present civilization, giving them a great advantage in determining the periodicy of long period comets

a longer period that adds up to a 2012 rendezvous is more statistically reliable than that of a short period comet. Every passage increases the chance of permutations due to encounters with the gravity of planets it may pass. A comet that has orbited 4 times in the last 2000 years is more likely to still be on course that one that has orbited unseen 50 times in the last 200 years.

Summary

Even without the possible return of Comet Caesar, dark comets are the leading contender for triggering a predictable 2012 cataclysm. Comets were known to the ancients - we have many ancient texts providing us with descriptive names like "fire from the sky" - and their cyclical nature makes it easy for any civilization with mathematical prowess to predict. Thousands of hypothetical dark comets remain undiscovered in modern times, and if we do find one on a collision course with our planet, we may only have a few years, or even a few days, to prepare. And those times will be times of mass panic.

Notes:

Steel, Rogue Asteroids and Doomsday Comets, 25. The longest observed orbital period for a comet is 153P/Ikeya-Zhang with 341 years, having been discovered in 1661, and again in 2002.

Gribbin, Fire on Earth, 103

Of course there is the possibility that the Great Comet of 1106AD and the 44BC comet are one and the same. If that were true, it could be expected to return circa 2250AD.

Lewis, Rain of Fire and Ice, 17

Parsons, Dark' comets may pose threat to Earth.

Asteroid Explosion over Indonesia

Nicholos Wethington

Space Fellowship
Mon, 02 Nov 2009 12:04 EST

This has taken awhile to filter into the Western press, but an asteroid exploded over the town of Bone, Indonesia on October 8th at around 11am local time.

Initially, locals called the police to report that a plane had crashed, or that an earthquake shook the ground, as reported in the Jakarta Globe. The Jakarta Post quoted Thomas Djamaluddin, head of the Lapan Center for Climate and Atmosphere Science Implementation as saying that the explosion was due to a meteorite or bit of space junk that had entered the Earth's atmosphere. As it turns out after further analysis, the explosion was due to an asteroid about 5-10 meters (15-30 feet) in diameter exploding in the air between 15 and 20 km (nine to 12 miles) above sea level. Nobody was injured as a result of the explosion, but it evidently caused quite a scare with the local population!

In a press release from the Near Earth Object (NEO) program, the explosion was detected by many International Monitoring System (IMS) infrasound stations, five of them 10,000 km (6200 miles) away, and one 18,000 km (11,100 miles) from the blast. These stations monitor seismic waves, infrasound (low frequency soundwaves), hydroacoustic, and radionuclide emissions as part of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). They are well equipped to monitor explosions of nuclear weapons, but also detect other events such as meteorite impacts and asteroid explosions, tsunamis and earthquakes.

When analyzed, the amount and intensity of low frequency sound waves created by the explosion allowed researchers Elizabeth Silber and Peter Brown of the Meteor Infrasound Group at the Univ. of Western Ontario to determine that the explosion caused by the asteroid was on the scale of 30 - 50 kilotons of TNT. To give you an idea of how powerful of an explosion this is, the bombs dropped over Hiroshima and Nagasaki in World War II exploded with the force of 20 kilotons of TNT.

A video of the explosion can be seen

The fireball - also called a bolide - created a dusty tail upon entering the atmosphere of the Earth. It is estimated that the asteroid was traveling around 72,000 km/hour (45,000 miles/hour) when it hit the atmosphere. As an asteroid enters the thick Earth atmosphere, it slows down abruptly and heats up due to the process of ablation. If this asteroid were made of metal instead of rock, it would likely have impacted the ground causing a lot of damage. Fortunately for the residents of Bone and the surrounding area, the rock broke up in a large fireball instead. There haven't been any reports of pieces that have touched down as of yet.

Asteroids of this size are predicted to impact the Earth about every 2-12 years, and the last one of this magnitude was a bolide over the Marshall Islands on February 1, 1994. That impactor was estimated to be between 4.4 and 13.5 meters. A full analysis of that event is available on the SAO/NASA Astrophysics Data System.

Of course, events like this always raise the question of why the object wasn't detected before it even entered the atmosphere. The NEO program has cataloged over 600 objects in the size of 10 meters, but there are many, many more out there. The cost of a monitoring and cataloging all of the Near Earth Objects would be in the hundreds of millions of dollars, but more events like this may spur the political will and capital to further efforts at protecting human lives from the potential damage of meteorite impacts.

California: Meteorite Sighting Startles Yolo County Residents

CBS13

Sat, 07 Nov 2009 07:08 EST

© Stephen Shaver/AFP/Getty Images
The Leonid meteor shower lights up the sky above China's Great Wall as stargazers brave the minus 20 degrees Celcius (minus 4 degrees Fahrenheit) temperature and walk up the wall with their flashlights 18 November, 2008 in Badaling

Authorities scrambled to find a downed aircraft after numerous witnesses called to report seeing a fireball plunge out of the sky, but the sightings may have been the result of something a bit more astronomical.

Yolo County emergency crews searched the area near Interstate 5 and Interstate 505 just northwest of Zamora after multiple callers reported seeing a ball of fire fall out of the sky, but found no sign of any aircraft.

An emergency dispatcher with the Federal Aviation Administration confirmed that the event is part of the annual Leonid Meteor Shower, which lasts for a couple of weeks and isn't expected to peak until November 17.

Visible meteors typically appear as shooting stars to the naked eye, but footage of other meteor sightings -- much of which is available on YouTube or other video sharing sites -- illustrate the spectacular potential of such events.

Authorities reported sightings all across Northern California, from the central coast into the Amador County, relating to the meteor shower.

Unusual meteorite found by time-lapse camera observatory

Sat, 07 Nov 2009 07:19 EST

American Museum of Natural History

© Phil Bland, Imperial College
Time-lapse image taken over one night of a fireball travelling across the sky. It was taken from a fireball camera network or observatory in Western Australia.

An unusual meteorite with an interesting orbit has been tracked to the ground using a photographic observatory that records time-lapse images of fireballs traveling across the sky.

The network of cameras is in the Nullabor Desert in Western Australia. It allows scientists to track a fireball path, formed by a meteorite as it travels through Earth's atmosphere, and then work out where the meteorite comes to rest.

The fireball camera network project was set up by Dr Phil Bland from Imperial College London and scientific associate of the Natural History Museum, along with colleagues from Ondrejov Observatory in the Czech Republic, and the Western Australia Museum, in 2006. This is the first meteorite recovered using the network.

The cameras recorded the fireball that ultimately produced the meteorite in 2007, and the fragments that fell to Earth were named Bunburra Rockhole after a local landscape feature near to where they landed.

The meteorite was found within 100m of the predicted fall line. It was collected and samples were given to the Natural History Museum where mineral experts Dr Gretchen Benedix and Dr Kieren Howard helped examine and classify it. They produced data about the meteorite's composition and the types of minerals within it.

Most meteorites found on Earth are believed to be fragments of asteroids - ancient rocks that formed during the creation of the solar system about 4.56 billion years ago.

Using complex calculations, the team were able to work out the meteorite's path to Earth and its orbit, and from that, where in the solar system the meteorite most likely came from.

The Bunburra meteorite is about the size of a cricket ball and is an unusual type of basaltic igneous rock. Most basaltic meteorites are thought to come from one asteroid. However, the composition of Bunburra Rockhole means that it comes from a different asteroid.

This means that the process required to form this type of rock was happening in more than one place in the early solar system.

'It's vital to have a meteorite with information about where it comes from in the solar system,' says Dr Benedix.

'We've known for a long time that most meteorites are from the asteroid belt, but we don't know exactly where. This kind of information helps us fit one more piece in the puzzle of how the solar system formed and evolved.

'The fact that this meteorite is compositionally unusual increases it's value even more. It helps us to uncover more information about the conditions of the early solar system.'

The team says that the meteorite had an unusual orbit. Using modeling techniques, it was determined that Bunburra Rockhole began as part of an asteroid in the innermost main asteroid belt between Mars and Jupiter.

Its orbit gradually evolved into one very similar to Earth's. Other meteorites for which data exist have orbits that take them into the main asteroid belt.

Dr Howard says, 'I consider myself lucky to handle rocks from space when usually I only know that they come from the curators' cupboard!

'The chance to study a meteorite with a known orbit and source, so soon after if falls to Earth, is really exciting.'

Dr Bland concludes, 'It was amazing to find a meteorite that we could track back to its origin in the asteroid belt on our first expedition using our small trial network.

'We're cautiously optimistic that this find could be the first of many and if that happens, each find may give us more clues about how the solar system began.'

Massive Fireball Over Tokyo

Sonotaco.jp

Sun, 08 Nov 2009 07:31 EST

Several people observed a massive meteor fireball emitting a brighter than usual flash at around 8:30 pm on the 6th of November - it was observed throughout the province. According to a statement from the Toyama Observatory, it was a "massive fireball", a rare phenomenon caused by a large mass of meteorite.

Watch the Sott web exclusive video below

The fireball was observed traveling in a northern direction. It lit up the skies for a full two to three seconds, falling to an area unknown at this time. The fireball divided into several individual pieces as the meteor exploded in the middle with a white, yellow, and red emission.

Usually when a meteorite enters the Earth's atmosphere, it burns up due to a super-heated atmospheric friction. It is often known as a "shooting star" -- But due to the size of this meteorite and its strong longer glow, it caused panic among large populated areas around the Tokyo vicinity.

Possible Meteor Spotted in British Columbia Sky

Sun, 08 Nov 2009 15:44 EST

CBC News

People throughout British Columbia were treated to a spectacular light show Saturday after what's believed to be a meteor lit up the sky.

Stephen Dalley and his wife were driving north of Comox, on Vancouver Island, at about 7 p.m. PT.

"We were shocked ... I mean, it wasn't what you'd expect, but it was bright white, with red and green and some blue colours, with a bit of a trail behind it and it was a large fireball," he said.

"[It was] approximately what the size of the moon would have been if we were looking at the moon."

Dalley said the intense light only lasted for about three seconds.

The streak of light was also seen about 500 kilometres northeast of Comox, near Vanderhoof.

In an email to CBC News, one witness in the area said, "a blue light flashed a moment before the meteor came down."

David Dodge, a retired astronomer who worked at the HR MacMillan Space Centre in Vancouver, said it was likely a rock from space.

He said this type of event is not unusual.

"These are happening all the time. We've had some very spectacular fireballs in the Malayasia area just a few weeks ago," he said.

"Earlier this year, there was a spectacular fireball that actually ended up in meteorites over Sudan, and a few weeks ago we had one over Vancouver, so these sorts of things are happening all the time."

Dodge said astronomers will use the sightings in the hopes of triangulating the spot where the rock may have landed.

California Fireball

Carl Hergenrother

The Transient Sky
Sun, 08 Nov 2009 06:38 EST

A brilliant fireball was seen over California during the early evening of November 7 at around 5:10 pm. Quite a few reports have been posted in the comments sections on this blog.

A comment posting by Rich gives a rather detailed observation of the event:

"11/07/2009 at approximately 1700hrs we were driving south form Santa Rosa on Hwy 12 and were passing through Sonoma when we noticed a large brilliant white fireball in a SSW direction. It first caught our attention at about 20 to 25deg off the horizon. Our visual on it only lasted only about 3-4 seconds then just before passing the hills in the distance it seemed to go out. There was no associated noise or sign of impact. It was just gone. There was a smoke or debris trail that we could see after the object was gone that was visible for perhaps a minute or so then it was dispersed by the wind."

Pictures of the residual smoke trail can be seen on the Spaceweather.com site.

Additional news stories were published by the Daily Democrat, San Francisco Chronicle, Contra Costa Times, and others.

The fireball was most likely caused by a small asteroid, probably no larger than a basketball. Though it is possible it may have been related to the Taurid meteor shower which is near its maximum in activity, it could easily be unrelated to any shower. The very bright slow fireballs are usually asteroidal in origin while meteor showers are usually produced by comets.

Comment: Another comment on that blog reads: Reg - November 9, 2009

On November 7, 2009 around sunset, I was driving northbound on US 101 15 miles south of Santa Maria, California. Fireball started directly north at approximately 40 degrees above the north horizon, headed vertically and burned-up (disappeared) approximately 3-5 degrees above the north horizon. Head of fireball well formed burning sphere, with long tail and sparks. At about 8 degrees above the horizon the head split into two pieces.

Pennsylvania: Another Fireball

jennyfire130

NowPublic
Mon, 09 Nov 2009 15:08 EST

I was driving home from an Apple Festival this weekend when my 3 year old daughter started shouting "Look Mama, a comet!!" I looked out the window and to my amazement I saw I HUGE yellow and white ball of fire. I immediately thought that I just witnessed a airplane explode in sky. I called my husband freaking out and he said that it was probably a meteor. I was driving on a highway and unable to pull over. I was able to reach into my purse and get out my camera. By the time I was able to get a photo through my front windshield (driving 55 miles/hr and one handed LOL) the fireball had broken into 4-5 smaller pieces. I am still not sure what exactly it was ... but it was really amazing and one of the coolest things I've ever seen in the sky! I am so excited to share my photo with you! Thanks for reading :)

Unknown Asteroid Buzzed Earth

Nancy Atkinson

Universe Today
Mon, 09 Nov 2009 04:00 EST

A previously undiscovered asteroid came within 14,000 km of Earth last week, and astronomers noticed it only 15 hours before closest approach. On Nov. 6 at around 16:30 EST a 7 meter asteroid, now called 2009 VA, came only about 2 Earth radii from impacting our home planet. This is the third-closest known non-impacting Earth approach on record for a cataloged asteroid.

Early on Nov. 6 the asteroid was discovered by the Catalina Sky Survey and was quickly identified by the Minor Planet Center in Cambridge MA as an object that would soon pass very close to the Earth. JPL's Near-Earth Object Program Office also computed an orbit solution for this object, and determined that it was not headed for an impact.

The two closer approaches include the 1-meter sized asteroid 2008 TS26, which passed within 6,150 km of the Earth's surface on October 9, 2008, and the 7-meter sized asteroid 2004 FU162 that passed within 6,535 km on March 31, 2004. On average, objects the size of 2009 VA pass this close about twice per year and impact Earth about once every 5 years.

Only thirteen months ago, another asteroid, 2008 TC3 was discovered under similar circumstances, but that one was found to be on a trajectory headed for the Earth, with impact only about 11 hours away. It impacted in a remote area of Africa; no one was injured and fragments have since been recovered for study.

Asteroid Impact Could Have Stirred the Ocean

Sid Perkins

Science News
Tue, 10 Nov 2009 09:26 EST

The collision of a large extraterrestrial object with Earth almost 2 billion years ago may have stirred the seas worldwide and delivered a huge serving of oxygen to the deep ocean.

The Sudbury impact, named after the Canadian city located near the center of what remains of the ancient crater, happened around 1.85 billion years ago (SN: 6/15/02, p. 378). Despite erosion since then, the impact structure - at least 200 kilometers across - is recognized to be the second-largest on the face of the planet, says William Cannon, a geologist with the U.S. Geological Survey in Reston, Va., and coauthor on a paper in the November Geology. The event fundamentally affected the concentrations of dissolved oxygen in the deep sea - enough to almost instantly shut down the accumulation of marine sediments known as banded iron formations, report Cannon and coauthor John F. Slack, also of the USGS in Reston.

Banded iron formations, massive deposits rich in iron oxides, have accumulated at several periods in Earth's long-distant geological past, mostly when atmospheric concentrations of oxygen were low (SN: 6/20/09, p. 24).

One extended episode of banded iron formation (or BIF) buildup suddenly - and without an obvious explanation - ended about 1.85 billion years ago, says Cannon. Over a very short interval, he notes, "the environment shifted from one happily making banded iron to one that wasn't."

In northern Minnesota and other areas nearby, the formations lie directly underneath a thick layer of material only recently recognized as ejecta from the Sudbury impact. Mark Jirsa, a geologist with the Minnesota Geological Survey in St. Paul, was a member of the team that identified the ejecta layer. "We intuitively connected the Sudbury impact with the shutdown of BIF accumulation," he says. "But now [Cannon and Slack] have come up with a model for how that might have happened."

About 1.85 billion years ago, Earth's now separate landmasses were joined in a single supercontinent. That also means there was one large ocean, says Cannon. Many scientists suggest that the object that slammed into Earth then - probably an asteroid abut 10 kilometers across - splashed down in that ocean, in waters about 1 kilometer deep on the shallow shelf surrounding the supercontinent. Models hint that the tsunami spawned by the event would have been 1 kilometer tall at the impact site and remained at least 100 meters tall about 3,000 kilometers away, Cannon adds.

Those immense waves and large underwater landslides triggered by the impact stirred the ocean, bringing oxygenated waters from the surface down to the ocean floor, the researchers propose. Sediments deposited on the seafloor before the impact, including BIFs, contained little if any iron in its Fe(III) form but were high in Fe(II), a sign that most parts of the ocean were oxygen-free. But marine sediments deposited after the impact included substantial amounts of Fe(III) but very little Fe(II) - and, therefore, sizable amounts of dissolved oxygen. The team's analyses suggest that after the impact, dissolved iron spewed into the deepest parts of the ocean by hydrothermal vents would have reacted with oxygen within a day or so, thereby choking off most of the supply of Fe(II) to shallower waters where BIFs typically accumulated.

While Cannon and Slack's model explains how BIF accumulation might have suddenly ceased 1.85 billion years ago, it doesn't prove that's how it happened, Jirsa warns. Nevertheless, he notes, "scientists are closer to an explanation than we previously were." The geological record suggests that environmental changes were happening in oceans worldwide even before the Sudbury impact, he adds, "and the role that the impact played, if any, in shutting down BIF accumulation isn't well understood."

Flashback: The Puzzle of the Half-Comet, Half-Asteroid

Wed, 05 Aug 2009 16:39 EDT

Technology Review

A mysterious object that ejects dust like a comet but orbits like an asteroid could be a new class of object in the solar system.

In 1996, astronomers identified an extraordinary object orbiting the Sun between Mars and Jupiter in a region best known for its asteroids. And yet this body, called 133P, defied description: it had the orbit of an asteroid yet emitted dust like a comet.

Clearly, this was a rare object. After centuries of observation, not a single other object in the asteroid belt had burped gas and dust in the same way.

So how could this have got there? According to Henry Hsieh at Queen's University, Belfast in Northern Ireland, there can be only two explanations. The first is that 133P is a comet that has somehow recently become trapped in an asteroid-like orbit. This would have required a hugely unlikely combination of gravitational kicks from other planets as the comet travelled into the solar system from the Kuiper Belt or Oort cloud.

Hsieh says this is so fantastically unlikely that it is almost certainly a one-off event. So there's almost no chance that we'd see another comet-like object in this kind of orbit.

The second explanation is that 133P is an asteroid formed partly of ice and that this is being released, perhaps by a collision with another asteroid. If this were the case, there would almost certainly be other asteroids with a similar makeup releasing dust. These we ought to be able to see.

So Hsieh set out to find one, making some 657 observations of 599 asteroids in the asteroid belt. The big news is that he has found one other object, called 176P/LINEAR, which is also emitting dust.

So it looks as if the mystery is solved. That more or less rules out the possibility that 133P is a captured comet. Instead, 133P and 176P are a new class of comet-like asteroids made up partly of ice, which is ejected whenever these objects are struck in the occasional unavoidable collision.

That's an interesting new addition to the asteroid menagerie. The only question now is what to call these beasts that are half comet and half asteroid. Comsteroids? Asteromets? Hsiehroids?
- -
Ref: arxiv.org/abs/0907.5505: The Hawaii Trails Project: Comet-Hunting in the Main Asteroid Belt:

The mysterious solar system object 133P/(7968) Elst-Pizarro is dynamically asteroidal, yet displays recurrent comet-like dust emission. Two scenarios were hypothesized to explain this unusual behavior: (1) 133P is a classical comet from the outer solar system that has evolved onto a main-belt orbit, or (2) 133P is a dynamically ordinary main-belt asteroid on which subsurface ice has recently been exposed. If (1) is correct, the expected rarity of a dynamical transition onto an asteroidal orbit implies that 133P could be alone in the main belt. In contrast, if (2) is correct, other icy main-belt objects should exist and could also exhibit cometary activity. Believing 133P to be a dynamically ordinary, yet icy main-belt asteroid, I set out to test the primary prediction of the hypothesis: that 133P-like objects should be common and could be found by an appropriately designed observational survey. I conducted just such a survey -- the Hawaii Trails Project -- of selected main-belt asteroids in a search for objects displaying cometary activity. I made 657 observations of 599 asteroids, discovering one active object now known as 176P/LINEAR, leading to the identification of the new cometary class of main-belt comets. These results suggest that there could be ~100 currently active main-belt comets among low-inclination, kilometer-scale outer belt asteroids. Physically and statistically, main-belt comet activity is consistent with initiation by meter-sized impactors. The estimated rate of impacts and sizes of resulting active sites, however, imply that 133P-sized bodies should become significantly devolatilized over Gyr timescales, suggesting that 133P, and possibly the other MBCs as well, could be secondary, or even multigenerational, fragments from recent breakup events.

[Paper: The Hawaii Trails Project: Comet-Hunting in the Main Asteroid Belt [PDF]]

Asteroid passes just 8,700 miles from Earth - with only 15 hours warning

Wed, 11 Nov 2009 00:59 EST

Daily Mail

It's getting frequent now

You almost certainly missed it - and luckily it missed you - but an asteroid has come within 8,700 miles of hitting the Earth.

Astronomers spotted the object only 15 hours before its closest approach to our planet last Friday.

Its orbit brought it 30 times nearer than the Moon, which is 250,000 miles away.

Even had it been on collision course with us, the 23ft wide asteroid - known as 2009 VA - is unlikely to have made much of an impact because it would probably have all but burnt up in the atmosphere.

It was picked up by the Catalina Sky Survey at the University of Arizona, then identified by the Minor Planet Centre in Cambridge, Massachusetts as a near Earth object and plotted by experts at Nasa.

US: Kansas father, son suspect meteorite landed at home

Associated Press

Tue, 17 Nov 2009 17:46 CST

A father and son have an extraterrestrial explanation for the strange rock that recently landed in their backyard in southwest Kansas. They are convinced it's a meteorite.

Chandler Harp, 10, was playing in the backyard of his Liberal home when he heard what sounded like an explosion about 15 feet from where he was standing. He looked over to see a plume of dirt and debris shoot 5 feet high.

At the bottom of a foot-deep hole, he found a 2-inch rock and showed it to his dad, Lee.

Once Lee Harp got a look at the metallic rock, he was certain it wasn't from this world. He said, "I knew he had a meteorite."

Fireball streaks through sky over Utah

Wed, 18 Nov 2009 12:42 EST

ABC4 News

A large ball of fire streaking across the night time skies just after midnight had many Utahn's wondering what they saw early Wednesday morning.

Dozens of calls came streaming into the ABC 4 newsroom with people wondering if they saw a shooting star, others wondered if it was the end of the world, military testing, or even a UFO.

People from Mona to Spanish Fork from Ogden to Bountiful all calling in a very similar sighting. To many, it looked like a large fall of fire, lightning up the sky, some say like daylight, others reported a blue like light that lasted for about 30 seconds. And many reported hearing a boom about 5 minutes later.

ABC 4 called Utah's NASA and Solar System Ambassador Patrick Wiggins who says that it was a meteor also known as a bolide. From his observatory near Stansbury Park he says the break up of the meteor occured at about 240 to 250 degrees azimuth which puts it just north of southwest. He also heard the sound of an explosion that would put the breakup of the bolide about 100 km in that direction placing it high above Granite Peak in the west desert.

We'd love to hear your stories of what you saw and what you heard from where you live. Please put your comments on our website and we'll be researching this today here at ABC4.

US: Fireball Lights Up Night Sky

Michael Coats

KIFI
Wed, 18 Nov 2009 12:40 CST

People from all over the Mountain West reported a "bright light" or "meteor streak" around midnight Wednesday morning.

Reports are coming in from Eastern and Southern Idaho, all throughout Utah and even Las Vegas.

Several viewers called into the Local News 8 newsroom reporting the bright light which lasted for just a few seconds.

Some have reported it as a "ball of light" and others called to say it looked more like a "green streak."

Media outlets in Salt Lake City report that some even felt a "slight rumble" or "sonic boom."

ABC sister station KTVX talked to NASA and Solar System Ambassador Patrick Wiggins.

Wiggins told KTVX that it was a meteor also known as a bolide. From his observatory near Stansbury Park, Utah, he said the break up of the meteor occurred at about 240 to 250 degrees azimuth which puts it just north of southwest.

He also heard the sound of an explosion that would put the breakup of the bolide about 100 km in that direction placing it high above Granite Peak in the west desert of Utah.
- -

© SLTrib/ Les Ashwood
A photo believed to be depicting the meteor's aftermath, taken at 7 a.m. Wednesday, Nov. 18, 2009, from Clive, in western Tooele County, looking east toward Salt Lake City.

Watch Twitter video from Utah:

Huge fireball explodes over western US

Wed, 18 Nov 2009 16:35 EST

SpaceWeather.com

As forecasters predicted, there was a surge of Leonid meteors during the late hours of Nov. 17th. Preliminary counts from the International Meteor Organization exceed 120 meteors per hour.

A remarkable midnight fireball that "turned night into day" over parts of the western United States last night was not a Leonid. Infrasound measurements suggest a sporadic asteroid not associated with the Leonid debris stream. The space rock exploded in the atmosphere with an energy equivalent to 0.5 - 1 kilotons of TNT.

Approximately 6 hours later, observers in Utah and Colorado witnessed a twisting iridescent-blue cloud in the dawn sky.

© Jeff Kendrick
Image taken: Nov. 18, 2009
Location: Looking South East of SLC, UT just before dawn 11/18/2009
Details: First appeared as a ring when the eastern sky was dark. Disappeared completely as the sun came up

© scott stringham
Image taken: Nov. 18, 2009
Location: Salt Lake City, Utah
Details: going to work witnessed this cloud. it was BLUE!!!

Debris from the fireball should have dissipated by that time, but the cloud remains unexplained; we cannot yet rule out a connection to the fireball event. Stay tuned for further analysis.

videos: #1, #2, #3.

US: Meteor the size of oven lights up the night sky, alarms Utahns

KSL

Wed, 18 Nov 2009 00:04 EST

A fast moving meteor lit up the night skies over most of Utah just after midnight Wednesday. Moments later, the phones lit up at KSL as people across the state called to tell us what they saw and ask what it was.

Utahns are still talking Wednesday about what scientists are calling a "remarkable midnight fireball." The source of all the excitement was basically a rock, falling from space. When a meteor enters the atmosphere, it gives off a lot of heat and light.

Folks at the Clark Planetarium say this rock was big--between the size of a microwave and washer-dryer unit.

At exactly 12:07, people from all over the western United States watched as the bolide meteor crashed into Earth's atmosphere. In some areas, the flash of light was so bright it caused light sensor street lamps to shut off.

Clark Planetarium Director Seth Jarvis said the stony meteorite was probably around the size of an oven, traveling 80,000 miles an hour when it hit our atmosphere and went splat like a bug on a windshield. He said it happened 100 miles up in the air, so despite the brightness, Utah was never in any danger.

"These collisions can do damage, but they are extremely rare, and literally once in a century do you observe something that's actually doing damage," he said.

Witness Andy Bailey said, "Oh, it lit up the whole sky, like almost brighter than the day. It was bright."

Don White was in Wyoming and told KSL Newsradio for a moment he suspected a nuclear strike. "With something that brilliant and that fast, it was like, whoa, did we just get hit or something? It would have been some bigger noise I guess if a nuclear device had gone off," he said.

"I've seen falling stars before, but nothing like that before," said witness James Albin.

We have reports that the light show was picked up as far away as Tucson, Santa Fe, Butte and Frisco Peak near Milford in southwest Utah.

The University of Utah has an observatory at 9,500 feet on Frisco Peak which captured images of the fireball itself.

Everyone who saw it has a once-in-a-lifetime story.

Resident Jon Olschewski said, "I noticed to the left something streaking through the sky. It was this meteor that was exploding. It was breaking off into at least five big chunks."

Many surveillance systems captured the spectacular blast of light.

"When you got this mass coming through the atmosphere, and these things are going fast, it's like if you could travel that fast on I-15, you could get from Salt Lake to St. George in a matter of 5 seconds. So these things are really going, hits the atmosphere and it makes so much pressure on its leading edge that it just shatters itself," Jarvis explained.

Roy Merrell also saw the light. He said, "There was this flash in the room, the room basically just lit up."

Others recorded a sequence of shadows as fantastic as any Hollywood studio could create.

Patrick Wiggins,NASA Solar System Ambassador to Utah, said, "To realize it was up so high, people are thinking it's right close, but the thing was up so high it was seen between L.A., Las Vegas and, of course, all over Utah. I mean, this thing was way up there."

Scientists believe it was not part of the famous Leonid debris stream, instead a sporadic asteroid, a midnight fireball, which exploded in the atmosphere with an energy equivalent of up to one kiloton of TNT.

"It was almost, I could say, like celestial," Olschewski said. "You know what I mean. One of those kind of moments like 'oh my gosh,' like 'I'm not ready' kind of thing."

In Tooele County, residents reported that they felt that moment when the meteor shattered. Wiggins said it took about 5 minutes for the sonic boom, but said he's not surprised people felt it.

"Most meteors, you don't hear them, but this one was close enough and big enough that yeah, you definitely heard the thing. It was exciting," he said.

Wiggins said, from his calculations, the pieces of the meteor likely fell over Dugway. He said it's possible meteorites could also be found elsewhere. He said it can't hurt to look around your yard; if you happen to find one it could be worth thousands of dollars.

KSL also received video clips of the meteor from Utah residents. Click on the video links to the right to watch the clips.

-----

Story compiled with information from Alex Cabrero, Shara Park, Mary Richards and Randall Jeppesen.

Kansas, US: Biophysicist confirms Liberal boy's meteorite discovery

Clara Kilbourn

The Hutchinson News
Wed, 18 Nov 2009 23:20 EST

The 2-inch-diameter gun-metal black rock that 10-year-old Chandler Harp found Saturday in his Liberal backyard traveled a long way to get there.

© The Hutchinson News/(Courtesy photo)
The triangle-shaped fresh iron meteorite discovered in Liberal fell to Earth from as far away as 100 million miles.

"There's no question in my mind whatsoever that what they have is a meteorite," said Don Stimpson of Haviland, a biophysicist who owns the Kansas Meteorite Museum and Nature Center on U.S. 54/400 near Greensburg.

Stimpson made the trip from rural Kiowa County to Liberal on Tuesday after he heard about the discovery of the meteorite by Chandler, son of Lee and Teri Harp.

The iron meteorite tumbled to Earth from the center of the atmosphere around the sun and fell from as far away as 100 million miles, Stimpson said.

"That's a part of the solar system that as humans we haven't investigated," he said.

It wasn't until after they launched an Internet search for meteorites that Lee and Teri Harp thought seriously about the bull's-eye in their backyard Saturday morning.

"It kind of scared us that they were in the backyard and a projectile was coming our way," Lee Harp said about the triangular object that could've hit their son or the family dog.

The meteorite was accompanied by what Chandler called a loud explosion, "twice as loud as a TV," and dirt that flew five feet into the air.

Stimpson, who has examined meteorites for the past 20 years, called the rock "beautiful, well-formed as it burned through the atmosphere."

Chandler's mother, a pharmacist, weighed it at 47 grams.

The dollar value of meteorites varies according to what meteorite hounds are willing to pay, Stimpson said, but could reach $100 per gram. At present there are about 1,500 meteorites posted for sale on the Internet.

Stimpson added that it's been a good year for meteorites in Kansas. Three new meteorites have been confirmed, at Larned, Sawyer, and a third awaiting absolute confirmation and naming, near the Smoky Hill River.

Their son's find isn't for sale, the Harps said. For now the meteorite will remain in a display case in their home.

The discovery hasn't changed Chandler's mind about a potential career.

Instead of exploring outer space, the fifth-grader said he still wants to be an engineer and build things.

US: Chunk of Ice Crashes Through Roof of Colorado Home

The Associated Press

Wed, 18 Nov 2009 15:25 CST

A basketball-sized chunk of ice crashed through the roof of a family's Colorado home after apparently falling from an airplane passing overhead. Danelle Hagan and her 9-year-old daughter were at home in Brush on Saturday when they heard the kitchen ceiling come crashing down. They were not injured.

"I hear a huge, what sounded like an explosion. And I look over and my kitchen is basically in shambles," Hagan told KMGH-TV in Denver. "It was very terrifying."

The Federal Aviation Administration was sending investigators to the home to investigate whether the ice came from an airplane. The Hagans put some of the ice in their freezer.

FAA spokesman Mike Fergus said Wednesday the ice chunk appears to be "Rime ice," which can build up on the outside of a plane's fuselage when it flies through cold and wet air.

Fergus says that it doesn't appear the ice was "blue ice," which comes from an airplane's toilet.

After investigators determine whether the ice came from a plane, Fergus said they'll look at which planes are in the area at the time to see if it's possible to tell which craft dropped the ice.

Fergus said that in cases of falling blue ice, FAA investigators would inspect any plane that was in the area to make sure it doesn't have a dangerous pressure leak. He said that ice falls from airplanes are alarming, but extremely rare.

He said the chances of getting hit by ice from a plane is "on the magnitude of a lightning strike."

Hagan's family is staying out of the house until it's repaired because the crash loosened some asbestos. She says people were in the kitchen just before the ice fell, so they're just glad to be OK.

"If we had been in that kitchen, it would have been devastating," Hagan said.

Comment: Extremely rare?

August 2007: Mysterious icy chunk smashes through roof in California

May 2007: Mysterious Chunk Of Ice Falls To Earth

January 2007: Car-destroying chunk may be icy meteor

January 2007: Ice Chunk Crashes Through Delaware Co. Home

April 2006: Ice crashes through college gym - No one is injured by the 2-foot chunk and no one knows yet where it came from

December 2005: Mysterious Ice Chunk Breaks Hole in Roof

December 2005: Ice chunk falls from sky in Japan

Mississippi, US: Sonic Boom's Source Still a Mystery

Karen Nelson

Sun Herald
Wed, 18 Nov 2009 15:09 CST

Keesler confirms jet training

Pascagoula - The boom that rattled windows in Pascagoula and Moss Point, swamped police phone lines and brought entire neighborhoods of people out of their homes to see what was happening was almost as much a mystery Wednesday as it was Tuesday night when it happened.

Keesler Air Force base told city police around 8:45 p.m. Tuesday the boom was caused by military jets on a training exercise in the Gulf, but that the jets were not from Keesler.

On Wednesday security at the base reconfirmed the jets had contacted the tower Tuesday night and were told there was a training exercise.

But what jets, and whose jets were flying at supersonic speeds over the Gulf at night?

Keesler didn't know. Pensacola Naval Air Station's Air Operations on the base said they weren't flying anything fast enough to cause a sonic boom at present and suggested only the Air Force would have the F-15 or fighter jets that could fit that bill.

They said Eglin AFB in Fort Walton Beach, Fla., was the best bet.

As it turns out, Eglin is the base that controls military training ranges - airspace over the Gulf of Mexico used for military maneuvers in this part of the Gulf.

Sgt. Brian Jones with Eglin's public relations office looked at the schedule for Tuesday night and said, "In our air space at those times all we had in the area were A-10s, and they're not fast enough to break the sound barrier."

He said the A-10s were firing guns, but did not discharge any heavy explosives during the maneuver.

Jones said he had no way of knowing if there had been a jet outside Eglin's airspace.

There were four booms on Tuesday. One at 8 p.m. rattled the east side of Jackson County all the way up to the rural northern regions, according to reports.

Then there was a series of three booms about 9 p.m., felt and heard in parts of Ocean Springs and Gautier to the west and in central Jackson County, as well as Pascagoula and Moss Point in the east. Then on Wednesday evening at about 8 p.m. at least one boom was felt in Ocean Springs, Vancleave and Pascagoula.

Laurie Shields, who lives on Ocean Springs Road near Interstate 10 said the 9 p.m. event on Tuesday shook her walls and made her roof rattle.

"You could hear the walls rattle it was so loud," she said.

A Moss Point resident said it moved pictures on her wall and caused her dogs to bark; a student at Trent Lott Academy in Pascagoula said his whole neighborhood came out of their houses and looked toward the Chevron Refinery. Another said the boom set off a neighbor's home security alarm.

And Capt. Shannon Broom with Pascagoula police said so many calls came in to the department it overwhelmed the phone lines and caused them to temporarily shut down.

Broom said Wednesday if training exercises were planned in the Gulf with jets that might create sonic booms, he'd like to have been warned ahead of time.

"They're the federal government, I guess they don't have to notify us, but it would have been nice," Broom said.

The U.S. is at war, so could there have been a super-secret maneuver?

Jones at Eglin said, "I'd tell you if there was something, and then I'd tell you we couldn't talk about it."

So that would be a "no."

The Air National Guard in Gulfport wasn't flying.

All the industry in Jackson County, including the refinery, reported in to the state Department of Environmental Quality and the city of Pascagoula that they were all clear, no incidents.

Pascagoula police checked with the U.S. Coast Guard.

Stennis Space Center in Hancock County said sometimes, with the right atmospheric conditions, rocket testing can bounce off cloud cover and travel a great distance.

But there was no rocket testing Tuesday night. That's scheduled for Friday.

NASA at the Houston Center, which also controls airspace over the western part of the Gulf, said it had nothing going on.

And the U.S. Geological Survey said although there had been 750 earthquakes in the United States in the past week, none was in or around the Gulf.

Earthquake? Isn't that a little far-fetched?

Well, a spokesman for the National Earthquake Information Center in Denver said earthquakes can cause noise when they hit.

But after listening to a description of the noise as a boom, he said the earthquake noise usually comes from the rattling rather than before the shaking.

Queensland, Australia: Green object that lit up sky a chip off an old meteor

Rodney Chester

The Courier-Mail
Fri, 20 Nov 2009 09:10 CST

Experts say a fire ball that streaked across the sky above south-east Queensland last night was a "chip off the old block of some asteroid".

The meteor was spotted by people from the Sunshine Coast, the Gold Coast and across Brisbane around 9.45pm.

Witnesses said the meteor was a green glow travelling from south-east to north-west, leaving a visible trail for 10 to 15 minutes.

Speaking on ABC radio this morning, Sir Thomas Brisbane Planetarium curator Mark Rigby ruled out space junk as an explanation.

"That's going the wrong way for space junk," he said. "Things are not launched in that direction."

Astronomers also dismissed the suggestion that the meteor was part of the Leonid meteor shower that is associated with the comet Tempel-Tuttle.

Every 33 years, the comet orbits the sun and leaves behind a dusty trail.

The meteor shower gets its name because the firey balls of dust seem to be coming from the direction of the constellation of Leo in the north-east.

While the Leonid meteor shower has created spectacular night shows some years, the meteor seen over Brisbane last night was at the wrong time and heading the in the wrong place.

The best place to see the Leonid meteor showers this year was in Russia, Kazak, China, Vietnam, Thailand, Nepal and India.

While the show usually lasts a few nights, the peak of the shower coincided with about 8am Brisbane time on Wednesday 18th.

Meteor turns night into day with bright explosion over South Africa

Sapa

TimesLive.co.za
Sun, 22 Nov 2009 10:44 CST

© Lunar and Planetary Institute, Universities Space Research Association
Satellite image of the Vredefort Dome meteor impact crater: South Africa is home to the world's largest and oldest (known) meteor impact crater

"What people saw last night was almost certainly a meteor," Claire Flanagan an astronomer at the Johannesburg Planetarium said.

People saw a bright "greenish, bluish" light heading towards Pretoria at about 11pm on Saturday night.

"It moved over the Gauteng Province towards Limpopo... it travels very fast and was about 90 kilometres up," said Flanagan.

The meteor was a hot topic of discussion in the forum on mybroadband.co.za.

"I saw a light flash the sky at about 8pm, at first I thought I was imagining it, but my friend also saw it," wrote someone who saw the meteor.

"... Maybe it's people getting abducted by aliens...I walked in the house looked out [and] the sky was lit. It looked how it normally [does] at 5am."

Another wrote: "I [saw] it too in Hartbeespoort dam. Almost looked like daylight for a few seconds, not sure if it was a meteor or not... pretty cool..."

Others claimed to have heard and seen a "bright explosion".

"I was in Lonehill sitting outside with some friends at around 11pm when my buddy noticed flashes in the distance. After he pointed, we looked up and that's when the sky lit up like day for a second or two. The sky actually went blue."

Flanagan said if a bang was heard, it meant that the meteor had disintegrated in the sky.

"The speed which it was travelling at would have caused it to burn and then disintegrate," she said.

Another user on the website said: "I think you guys should relax. It's Wikus Van der Merwe and his prawns," in reference to the South African-made movie 'District 9' which sets Johannesburg as the home of alien creatures.

Flanagan said that if the meteor had landed it would not have caused a major impact.

She could say how big it was as it was unexpected, and not connected with any kind of shower, but said the planetarium would be investigating the incident.

Comment: Update: This is allegedly a video of "the meteor that passed through South Africa and landed in Botswana on Saturday":

Mystery lights pass over Moutere area

Alistar Paulin

The Press
Tue, 24 Nov 2009 16:27 CST

No-one used the word UFO but the lights seen in the sky over Upper Moutere, near Nelson, last night are definitely unidentified.

Several people reported seeing balls of fire in the sky about 9.30pm, with Matiu Noakes saying he saw nine, moving from the direction of Kina toward Upper Moutere. "They looked like skydivers coming down with flares attached to them."

He said they faded out over Upper Moutere and were going too fast to be flares.

Lisa Chambers, marketing manager for Skydive Abel Tasman and a keen member of Nelson's skydiving community, said "there is absolutely no way it could have been skydivers". She said night drops were too dangerous in that area and had there been a prank afoot, she would have known.

Mike Reed, a helicopter pilot, said he was driving toward Motueka along the Moutere Highway when he saw the lights. He saw several other cars parked at the turnoff to Neudorf Rd, and spoke to others there who had been watching the lights.

He said he expected to hear aircraft noise when he turned off his engine but it was completely silent. Even so, he double-checked with air traffic control at Nelson Airport, which knew of no aircraft in the sky nearby at the time.

He said the lights were below the clouds, which he estimated to be about 300 to 500 metres up, and one of them appeared to float up into the clouds.

"If I was going to take a guess on it, I would say somebody's got a bunch of helium balloons and they've tied something on to it." But he had discounted every theory he had come up with so far.

Astronomer Robert Rea, of the Nelson Science Society, said he doubted anything astronomical would have pierced last night's cloud cover. Motueka police said they received no calls.

US: Mysterious 'fireball' sighting over Massachusetts not science fiction

Lynne Hendricks

The Daily News
Fri, 27 Nov 2009 10:58 EST

As Ernest Merrill was driving down Route 113 in West Newbury on Saturday night, he glimpsed what many astronomers refer to as a once-in-a-lifetime sighting - a fireball falling from the sky.

Merrill's friends think he's crazy, but scientists say it's entirely possible. Referred to by astronomers as a "fireball," it is caused by a larger-than-average particle, perhaps from a Leonid meteor shower, shooting through the earth's atmosphere and blazing a fiery trail to the treeline.

The object was like nothing 67-year-old from Salisbury and his wife, Laura, had ever seen before.

"We were riding along, and it was dark," Merrill said. "We were talking about the moon, and all of a sudden this thing came into the Earth's atmosphere and was shooting across the sky with a tail, like fire coming off and going all the way toward Haverhill. We watched it going down, and it finally disappeared by the trees. It came into the Earth's atmosphere and it was burning up as it was coming down."

Shooting stars have been plentiful this month, though the peak opportunity to see one from the 2009 Leonid meteor shower passed on Nov. 17. But some days after Earth passed through the field of comet debris that causes the cascade of stars, stargazing enthusiasts are still reporting mysterious objects streaming across the horizon.

It was approximately 5:30 p.m. when the object appeared out of nowhere, Merrill said, and that's just how sightings occur for lucky Earth dwellers fortunate enough to be looking upward when one of the rare fireballs makes its way to Earth, said Kevin Ackert of the North Shore Amateur Astronomy Club out of Groveland.

"Most people get to see something like that maybe once or twice in a lifetime," said Ackert, who had a similar experience many years ago while driving on Interstate 93 toward Concord.

The object Ackert saw exploded upon impact with Earth's atmosphere, lighting up the night sky with four distinct trails of debris, then disappearing again. But that's not what stargazers typically see during a meteor shower.

That fiery display, similar perhaps to what Merrill saw on Saturday, is a rare occurrence that meteor experts track as "fireball sightings," but have a hard time capturing on film due to their unpredictable nature. It was an unusual sight for Merrill, who's still not sure it could be classified as something from a common meteor shower. And he's not the only one who saw it.

Merrill said he called his daughter, Laurie, in Nashua, New Hampshire, following the sighting, and she said she saw it as well. And when he and his wife reached their destination - Building 19 in Haverhill - on Saturday night they told their story and found another woman in the store had seen the object blaze across the sky, too.

But when Merrill called the police, they claimed to his astonishment that they had received no reports of strange, unidentified flying objects in the area.

"Are we cracking up or something?" Merrill recalls thinking on learning no one had reported the sighting. "This thing was big. If I took a ruler and put it up to the sky, this thing would be 6 inches wide in the sky."

Larger-than-average meteors are often seen in association with known meteor showers, according to NASA's informational data compiled on meteor showers. And Ackert believes it's possible the Merrills saw a larger-than-average fragment from the comet Temple Tuttel, which spurred the debris field known as Leonids as it orbited the sun in 1466. The Earth sidles close to that debris field every 33 years or so and produces spectacular meteor storms every November for the few years surrounding the peak, he said.

"It was most likely from Leonid," said Ackert of the fireball. "The Leonid period this year, you could see from the 16th right through the 20th. It's even possible to see it a little later."

As an amateur astronomer with a day job working for a property management company, Ackert serves as treasurer of the Northshore Amateur Astronomy Club, a nonprofit, 501-3 company that holds star parties in schools across the Merrimack Valley to introduce them to the constellations and to stargazing.

According to the American Meteor Society, the Merrills also could have seen something emanating from another, lesser known meteor shower that hit its peak Saturday night. While the Leonids were present from Nov. 10-21, the Alpha-monocerotids, so named for originating near the Monoceros constellation, peaked on Nov. 21 and was to be detectable in the night sky through last night.

Accompanied by a waxing crescent moon Saturday, the unpredictable shower has been known to become visible every 10 years and presents for a short, spectacular burst of up to 400 meteors an hour.

"The way to tell if it's a Leonid is when you see it, draw an imaginary line back from the direction that it came from," Ackert said. "If it came from the direction of Leo the Lion, it's a Leonid."

An Alpha-monocerotids would originate from the direction of Orion, according to experts.

For those who might have missed the fireball across West Newbury, as well as the popular Leonid shower, take heart. The Geminid meteor shower will peak on Dec. 14, and the moon will again be favorable for good viewing, Ackert said.

Merrill, who keeps a $300 telescope in his basement that he picked up for $15 at a yard sale, has been inspired to dust it off and use it. He's even thinking of investing in one with a better capacity.

"I'm 67 years old, and I've never seen anything like that," he said. "I'd like to find out how many people saw this. One in a million chances, and I saw one."

Comment:

That fiery display, similar perhaps to what Merrill saw on Saturday, is a rare occurrence that meteor experts track as "fireball sightings,"

As regular Sott readers know, fireball sightings are not all that rare now. All one needs to do is put the word fireball, or meteor in our search engine and you will see lots of reports of these "rare" sightings.

Canada: Fireballs spotted in Edmonton sky

Richard Warnica

Edmontonjournal.com
Fri, 27 Nov 2009 09:45 EST

Ah to be an early riser: first to the paper, first to the coffee, and, of course, first to the occasional fireball scorching through the sky.

Twice in as many mornings this week early birds have reported fiery objects in the atmosphere above Edmonton.

On Thursday at about 7:15 a.m., a fireball was spotted travelling low along the horizon from the northeast to the east, according to the Telus World of Science. The next day, on Friday, a second was eyed in the west at about 5:50 a.m.

The reports come just over a year after a spectacular meteor lit up Edmonton's skies as it disintegrated in the atmosphere on Nov. 20, 2008.

Parts of that celestial missile crashed into the earth and were found in fields near Buzzard Coulee, Sask., just south of Lloydminster. But the remaining chunks of these most recent meteors will be much harder to find, said Francis Florian, the director of public programming at the World of Science.

The Buzzard Coulee meteor was seen by hundreds of people and burst through the atmosphere at a steep angle, limiting the area of search.

"The one seen yesterday morning seemed to be coming in at a much shallower angle," Florian said. That means it's less likely to have made it through the atmosphere at all.

"If it did peter out and it did make it down to the earth, the areas of search would be much greater ... maybe even hundreds of kilometres."

Anyone who saw the meteor is asked to make a formal report to the Canadian Fireball Reporting Centre at the University of Calgary. The more reports they get, the better chance they have of finding out if and where any meteorites will be found.

England: Vertical Flames Seen in the Sky Above Liverpool

UK UFO Sightings

Sun, 29 Nov 2009 09:51 EST

Posted: November 28, 2009

Location of Sighting: Princess Ave.Toxteth, Liverpool
Date of Sighting: 26th November
Time: 6.10pm

Witness Statement: I had just crossed the road when I turned to the right of me in the sky I saw flames that looked like they were in a furnace, the flames were going up like it was contained in something I could see no out line it moved in a loop towards Smithdown Road,

It seemed strange as the flames were vertical and not horizontal as you might expect, if it was coming out of an engine. It had a mechanical feel about it like something out of Flash Gordon. The flames were orange.

Solo Sailor Spots Pacific Bolide

Peter Lake

Universe Today
Sat, 28 Nov 2009 07:21 EST

"It was so bright and big that I was actually a bit spooked before realizing what it was."

A 16-year-old high school girl who is attempting to sail solo around the world spotted a bright bolide over the Pacific Ocean during the peak of last week's Leonid meteor shower. The International Meteor organization relies on reports just like this from observers in the field....or in this case "all at sea".

Jessica Watson a student from Queensland, Australia, has set off on the adventure of a lifetime, attempting to become the youngest woman to sail solo and unassisted around the world.

Jessica's blog has been quite popular and many people have been leaving messages of encouragement and checking on her daily progress. The plucky teenager has endured a rigorous preparation and good deal of media controversy, but retains a sense of purpose and wonderful support from her family, sponsors and supporters as she reached the first major milestone and crossed the equator in her yacht - Ella's Pink Lady.

Keen to offer my own message of support, I left a comment on her blog regarding the Leonid meteor shower, and suggested if she was looking for activities to keep her mind occupied that she might consider doing a few meteor counts in the night watch.

Imagine my surprise when on the 18th Jessica's lead blog entry commenced with the sighting of a brilliant bolide.

"I'm not much of an Astronomer but with all this talk of meteor showers last night, I was keeping an extra good eye out and did see the most amazing shooting star," Jessica reported.

According to Jessica's sked, she was travelling in a north-easterly direction, south of the equator, and west of Jarvis Island near Kirabati - basically in the middle of a Pacific Ocean. While it is impossible to say if it was a Leonid Meteor, it certainly made an impression.

Jessica's account follows:

"It was so bright and big that I was actually a bit spooked before realizing what it was. But I can't tell you what I wished for though!".

Many of the visitors to Jessica's Blog commented on it being a good luck "sign" as she crossed the equator.[...]

USA: Calculations estimate meteor lit up 500,000 miles

John Hollenhorst

ksl.com
Mon, 30 Nov 2009 22:00 EST

Salt Lake City -- Space buffs have some astounding new calculations about the gigantic fireball that lit up our part of the west two weeks ago. They now estimate the meteor lit up 500,000 square miles bright as day, and they've learned a lot more by studying some spectacular images.

A lot of what people thought is turning out to be wrong. The Nov. 18 fireball was apparently much higher and farther away than it appeared, never closer than 120 miles to Salt Lake City, which makes its brightness all the more amazing.

Dash-cam video from a police car in Grand Junction, Colo, provided vital clues to meteor trackers. Almost 300 miles away, it shows the fireball lighting up the sky, all the way on the opposite side of Utah.

Seth Jarvis of Clark Planetarium calls it God's flash bulb, briefly illuminating a half million square miles.

"From our area here, it was as bright as the sun," he said.

In surveillance video from the Salt Lake valley, the Wasatch Mountains turn from midnight to noon, as if a zillion-watt light bulb switched on.

"In the trillions of watts of power, which is a fair percentage of the power being consumed by the United States of America," Jarvis said.

Meteor trackers measured the angles of moving shadows in video of the meteor. Using textbook trigonometry, they worked out the angle and trajectory of the meteor.

"I'm estimating it entered the atmosphere at about 50,000 miles an hour," Jarvis said.

With the Colorado video and a spectacular mountaintop video from western Utah, they triangulated a new target zone. The space rock evidently traveled north to south and exploded 35 miles high, 120 miles west of Salt Lake.

If any of it reached Earth, it was likely south of Wendover, near the Utah-Nevada border in the rugged Deep Creek Mountains.

"Which is a pretty nasty place to have to go hunt for rocks, because there's plenty of rocks already out there," Jarvis said.

Professional meteorite hunters have also done the same calculation, and teams of searchers are already in the Deep Creek Mountains.

Photos taken the next morning seem to show two smoke rings. It may be an echo of the double flash or double explosion noticeable on some videos.

Jarvis explained, "There's lots of other natural phenomena that can create interesting looking clouds that high up in the sky. And it could be military jets maneuvering, any number of things; however, there are a lot of things that sort of line up in favor of that being the smoke trail left by the meteor."

Jarvis says meteors like this enter the atmosphere all the time but usually over oceans, uninhabited ground, or at times when no one is looking. For a populated place like Utah, the Nov. 18 event was practically a once-in-a-lifetime experience.

NASA considering mission to send astronauts to asteroid, as stepping stone to future voyage to Mars

Kevin Flynn

New York Daily News
Tue, 24 Nov 2009 14:36 CST

A TV space hit of the future could be 2020 Rock.

That's the rough target date NASA and space industry folks are eying for a mission to send astronauts to a Near Earth Object, aka an asteroid. Such a trip could be a stepping stone to Mars and extended stays on the moon, and guide plans to head off dangerous space rocks on a collision course with Earth, according to Space.com.

Lockheed Martin, builder of the next-generation Orion spacecraft, the U.S. space program's successor to the shuttle, has drawn up a "Plymouth Rock" plan for NASA touting the voyage as a way to gain a foothold outside low-Earth orbit. Powerful telescopes and beaming energy to Earth from space could be the eventual payoff.

The merits of a human mission to a Near Earth Object were detailed last week during a Boulder, Colo., meeting of the Small Bodies Assessment Group, established by NASA in 2008 to study asteroids, comets, interplanetary dust, small satellites and far-flung orbiters known as Trans-Neptunian Objects.

The plans are to be weighed by NASA and the White House, Paul Abell, a research scientist at the Planetary Science Institute assigned to the Johnson Space Center in Houston, told the Web site. "It's going to take a bit of time. I don't think there's going to be a quick decision."

How the White House will react to an asteroid trek is beyond anybody's crystal ball, Space.com said, but the talk got the attention of Lockheed Martin, which began its Plymouth Rock mission study a couple years ago, said Lockheed's Josh Hopkins, in the company's advanced programs for human space flight division in Denver.

Maximizing astronaut safety and coping with issues such as trash management, cosmic rays and abort scenarios are still up in the air, Hopkins noted. But given the core attributes already built into the Orion system, he said, "we think it does make sense for the human spaceflight program to be investigating this."

But there would be no landing on the asteroid. Instead, astronauts would park nearby and jet-backpack to the surface. They'd expect to haul back about 200 pounds worth of rock, gathering data about the makeup of the objects that could be useful if one of them were found hurtling toward the Earth someday.

"We assume staying at the asteroid for five days. They could stay a week or two. But staying for a month gets hard," Hopkins said.

"We'd really like a larger pool of candidate targets so that we could visit a NEO that has cool properties and would have the greatest scientific return," Chapman told Space.com.

"Human exploration is for human purposes," said Mark Sykes, chair of the Small Bodies Assessment Group and director of the Planetary Science Institute in Tucson.

Science by itself doesn't drive human exploration, Sykes noted, "but we can benefit, scientifically, from this. We'll take advantage of whatever opportunities come our way!"

Sykes said the prospect that space rocks could hold resources, such as a cache of water, or be useful in radiation shielding, may have a profound impact on expanding sustainable human operations farther out into space, Space.com reported.

If so, asteroids may well act as a linchpin for people living, working and populating space, Sykes said. But are those resources recoverable in an economic way?

"It's within the realm of consideration. Of course, a lot more homework needs to be done," Sykes stressed.

October 2009

2009-10-28T05:05:00.005Z

Video: Fireball lights up sky over Iceland

mbl.is
Mon, 05 Oct 2009 16:43 EDT

A police dash-cam catches a fireball lighting up the sky in the south of Iceland

Translation of article:

The police in Selfoss caught these weird lights in the sky on tape shortly after midnight last night. The officers were going east during a routine highway patrol on Eyrarbakka-road when they noticed a spectacular flare which to them seemed to be heading to the river Ölfusá. Speculations are that this was a meteorite entering the atmosphere.

Many saw the flare and notified the police, and the flare was seen all around the south of Iceland and in Akranes. It is believed impossible to have been an emergency flare.

The sheriff in Selfoss says there has not been any aftermath to his knowledge, and no unusal visitors have been seen that could possibly have fallen from the sky.

Quick Rebound From Marine Mass Extinction Event, New Findings Show

Science Daily
Sat, 03 Oct 2009 19:55 EDT

© Don Davis/NASA
An artist's rendering of the asteroid impact that took place 65 million years ago and likely killed off nearly every large vertebrate species on the planet, including, many think, the dinosaurs.

In 1980, Luis Alvarez and his collaborators stunned the world with their discovery that an asteroid impact 65 million years ago probably killed off the dinosaurs and much of the the world's living organisms. But ever since, there has been an ongoing debate about how long it took for life to return to the devastated planet and for ecosystems to bounce back.

Now, researchers from MIT and their collaborators have found that at least some forms of microscopic marine life - the so called "primary producers," or photosynthetic organisms such as algae and cyanobacteria in the ocean - recovered within about a century after the mass extinction. Previous research had indicated the process might have taken millions of years.

It has taken so long to uncover the quick recovery because previous studies looked mostly at fossils in the layers of sediment from that period, and apparently the initial recovery was dominated by tiny, soft-bodied organisms such as cyanobacteria, which do not have shells or other hard body parts that leave fossil traces. The new research looked instead for "chemical fossils" - traces of organic molecules (compounds composed of mostly carbon and hydrogen) that can reveal the presence of specific types of organisms, even though all other parts of the organisms themselves are long gone.

The new research, published in the Oct. 2 issue of Science, was led by Julio Sepúlveda, an MIT postdoc who carried out part of the work while still a graduate student at the University of Bremen, Germany, and MIT Professor of Geobiology Roger Summons, among others.

The team had two major advantages that helped to make the new findings possible. One was a section of the well-known cliff face at Stevns Klint, Denmark, that happens to have an unusually thick layer of sediment from the period of the mass extinction - about 40 centimeters thick, compared to the few cm thickness of the layers that Alvarez originally studied from that period at Gubbio (Italy) and Stevns Klint (Denmark). And team members tapped one of the most powerful Gas Chromatograph-Mass Spectrometers (GC-MS) in the world, a device that can measure minute quantities of different molecules in the rock. MIT's advanced GC-MS is one of only a few such powerful instruments currently available at U.S. universities.

When people look at microfossils in the sediments from the period but are unable to detect the chemical biomarkers with the level of sensitivity the MIT team was able to achieve, they "miss a big part of the picture," Sepúlveda says. "Many of these microorganisms" that were detected through molecular signatures "are at the base of the food chain, but if you don't look with biochemical techniques you miss them."

The analysis clarified the sequence of events after the big impact. Immediately after the impact, certain areas of the ocean were devoid of oxygen and hostile to most algae, but close to the continent, microbial life was inhibited for only a relatively short period: in probably less than 100 years, algal productivity showed the first signs of recovery. In the open ocean, however, this recovery took much longer: previous studies have estimated that the global ocean ecosystem did not return to its former state until 1 to 3 million years following the impact.

Because of the rebound of primary producers, Sepúlveda says "very soon after the impact, the food supply was not likely a limitation" for other organisms, and yet "the whole ecology of the system remained disrupted" and took much longer to recover.

The findings provide observational evidence supporting models suggesting that global darkness after the impact was rather short. "Primary productivity came back quickly, at least in the environment we were studying," says Summons, referring to the near-shore environment represented by the Danish sediments.

"The atmosphere must have cleared up rapidly," he says. "People will have to rethink the recovery of the ecosystems. It can't be just the lack of food supply" that made it take so long to recover.

The team hopes to be able to study other locations with relatively thick deposits from the extinction aftermath, to determine whether the quick recovery really was a widespread phenomenon after the mass extinction.

These findings seem to rule out one theory about how the global ecosystem responded to the impact, which held that for more than a million years there was a "Strangelove ocean" - a reference to the post-apocalyptic scenario in the movie Dr. Strangelove - in which all the primary producers remained absent for a prolonged period, Summons says.

In addition to Sepúlveda and Summons, the work was carried out by Jens Wendler of the Friedrich-Schiller University in Jena, Germany, and Kai-Uwe Hinrichs of the University of Bremen. The work was funded by the DFG, European Graduate College Europrox and the NASA Astrobiology and Exobiology Programs.

Journal reference:

1. Julio Sepúlveda, Jens E. Wendler, Roger E. Summons, and Kai-Uwe Hinrichs. Rapid Resurgence of Marine Productivity After the Cretaceous-Paleogene Mass Extinction. Science, 2009; DOI: link

Zadunaisky's Math Determined Halley's Comet Orbit

Associated Press / Boston.com
Wed, 07 Oct 2009 20:20 EDT

Buenos Aires, Argentina - Pedro Elias Zadunaisky, an Argentine astronomer and mathematician whose calculations helped determine the orbit of Saturn's outermost moon, Phoebe, as well as Halley's Comet, died Wednesday. He was 91.

Zadunaisky was a pioneer in celestial mechanics, applying mathematical models to determine how gravity and other forces alter the orbits of other objects in the solar system.

Zadunaisky also was a Senior Astronomer at the Smithsonian Astrophysical Observatory and in the 1960s researched the orbits of celestial bodies at NASA's Goddard Space Flight Center, calculating the orbits of the first U.S. Earth satellite, Explorer I, as well as other satellites during the U.S. space race against Russia.

Born in the Argentine city of Rosario on Dec. 10, 1917, Zadunaisky earned a civil engineering degree at the National University of Rosario, then pursued applied mathematics and specialized in celestial mechanics. He earned three Guggenheim fellowships for research at Columbia University in 1957, Princeton University in 1958 and at the University of Texas at Austin in 1977.

Zadunaisky left Argentina in 1966 along with many other professors and scientists after a crackdown on university protests against a military coup known as "the night of the long clubs."

Zadunaisky soon returned, and eventually taught at both the University of Buenos Aires and the National University of La Plata. He also directed astrodynamical investigations at Argentina's National Commission on Space Activity.

In 2000, an asteroid discovered by a team of his former students was named 4617 Zadunaisky in his honor.

His research was published in more than 40 publications worldwide, including the text book A Guide to Celestial Mechanics, edited by the Harvard Smithsonian Center for Astrophysics.

What (Maybe) Didn't Kill the Dinosaurs: Comets

John Matson
Scientific American
Thu, 01 Oct 2009 00:01 EDT

© Bettmann Corbis
Cometary commotion: A new mechanism for how icy bodies get past Jupiter and Saturn suggests that comet showers did not play a big role in Earth's extinctions.

A new model for comet production revises the theory of their origins

The chunks of ice and dust that make their home in the Oort cloud, far beyond the orbit of Pluto, sometimes become dislodged and head into the solar system as streaky comets. Some disruptions, caused by passing stars and other interactions with the Milky Way galaxy, are severe enough to send Oort comets into orbits that buzz or even collide with Earth. New simulations have revealed a novel mechanism for their entry into our part of the solar system, a method that also suggests that comet showers may not have been strongly involved in major extinctions on Earth.

Comet dynamics depend heavily on Jupiter and Saturn: their huge gravitational fields tend to keep objects away from Earth. Comets that manage to skirt Jupiter and Saturn, the conventional thinking goes, had to have originated in the outer reaches of the Oort cloud, where perturbations from outside the solar system can be felt most strongly and are writ large across vast cometary orbits that take hundreds of years to complete. Only during comet showers caused by close stellar passages, the theory holds, have extreme gravitational disruptions brought inner Oort cloud comets into the mix.

A computer simulation by Nathan Kaib and Thomas Quinn, both at the University of Washington, have upended this thinking. They have found that the comets that manage to cross the Jupiter-Saturn barrier do in fact originate in large numbers in the inner Oort cloud, even in the absence of a large disruption causing a comet shower. Specifically, they found that the relatively nearby objects of the inner Oort cloud can be kicked into the reaches of the outer cloud via interactions with the massive planets. Those newly far-flung comets, suddenly enjoying a longer orbit and greater gravitational perturbations from interstellar space, can find their orbits so changed that, by the time they pass through the planetary region again, they slip past the gas giants. "They can basically hop over the Jupiter-Saturn barrier," Kaib says.

Kaib and Quinn estimate that more than half of the comets we observe streaking in from the Oort cloud reach our neighborhood via this route, and other researchers agree the simulation appears valid. "This mechanism, this dynamical path, as we call it, could work and could be a significant contributor," says Paul Weissman, a senior research scientist at the NASA Jet Propulsion Laboratory.

The new research presents a route for comet production "that goes some way" toward resolving discrepancies between the standard model and the observations, says Scott Tremaine, an astrophysicist at the Institute for Advanced Study in Princeton, N.J. "One of the issues is that [the conventional view of] the cometary formation process is so inefficient; in order to produce the number of comets that we see, you'd need a really massive protoplanetary disk, one that appears to be incompatible with our best estimates from other sources," Tremaine says.

Kaib and Quinn used their newfound mechanism, as well as the number of observed comets, to estimate an upper limit on how much material could be in the inner Oort cloud. They then produced a statistical model of how many comets would have hit Earth in comet showers in the past several hundred million years. Their conclusion: large cometary showers were few and hence probably did not cause more than one extinction event.

Using cometary dynamics to unwind the extinction history on Earth will likely meet with some controversy. Weissman notes that the extinction implications of Kaib and Quinn's analysis would involve comet showers, not comets in general, and that even a diminished profile of showers does not rule out the role of comets in extinctions. One big strike, rather than a shower of small ones, is all that's needed to trigger extinctions, he points out.

NASA Refines Asteroid Apophis' Path Toward Earth

Jet Propulsion Laboratory
Mon, 12 Oct 2009 19:52 EDT

Pasadena, California -- Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036.

The Apophis asteroid is approximately the size of two-and-a-half football fields. The new data were documented by near-Earth object scientists Steve Chesley and Paul Chodas at NASA's Jet Propulsion Laboratory in Pasadena, Calif. They will present their updated findings at a meeting of the American Astronomical Society's Division for Planetary Sciences in Puerto Rico on Oct. 8.

"Apophis has been one of those celestial bodies that has captured the public's interest since it was discovered in 2004," said Chesley. "Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million."

A majority of the data that enabled the updated orbit of Apophis came from observations Dave Tholen and collaborators at the University of Hawaii's Institute for Astronomy in Manoa made. Tholen pored over hundreds of previously unreleased images of the night sky made with the University of Hawaii's 2.2-meter (88-inch) telescope, located near the summit of Mauna Kea.

Tholen made improved measurements of the asteroid's position in the images, enabling him to provide Chesley and Chodas with new data sets more precise than previous measures for Apophis. Measurements from the Steward Observatory's 2.3 meter (90-inch) Bok telescope on Kitt Peak in Arizona and the Arecibo Observatory on the island of Puerto Rico also were used in Chesley's calculations.

The information provided a more accurate glimpse of Apophis' orbit well into the latter part of this century. Among the findings is another close encounter by the asteroid with Earth in 2068 with chance of impact currently at approximately three-in-a-million. As with earlier orbital estimates where Earth impacts in 2029 and 2036 could not initially be ruled out due to the need for additional data, it is expected that the 2068 encounter will diminish in probability as more information about Apophis is acquired.

Initially, Apophis was thought to have a 2.7 percent chance of impacting Earth in 2029. Additional observations of the asteroid ruled out any possibility of an impact in 2029. However, the asteroid is expected to make a record-setting -- but harmless -- close approach to Earth on Friday, April 13, 2029, when it comes no closer than 29,450 kilometers (18,300 miles) above Earth's surface.

"The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL. "The public can follow along as we continue to study Apophis and other near-Earth objects by visiting us on our AsteroidWatch Web site and by following us on the @AsteroidWatch Twitter feed."

The science of predicting asteroid orbits is based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids.

NASA detects and tracks asteroids and comets passing close to Earth using both ground and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. Cornell University, Ithaca, N.Y., operates the Arecibo Observatory under a cooperative agreement with the National Science Foundation in Arlington, Va.

Cosmic Object Caught On Camera

koat.com
Tue, 13 Oct 2009 02:15 EDT

A New Mexico astronomer is hoping you can help solve a mystery.

He caught a spectacular fireball on video and he said you can help him track down what's left of it.

Thomas Ashcraft caught a cosmic fireball on camera. It flashed through the sky for about eight seconds just after 2 Friday morning.

"Probably originating in the vicinity of Taos, and then streaking across the sky to Wagon Mound or Springer area," said Ashcraft.

Ashcraft works in a lab the size of a small barn. He bought or built most of the electronics himself, except for a special camera on loan from Sandia Labs.

The camera looks like a parking lot surveillance camera except it's parking lot is the sky.

"Actually up to Denver, into Utah, into southwest Kansas, and northern Mexico," said Ashcraft.

The camera runs from dusk to dawn recording everything that flashes through the heavens. It's synched to a radio telescope that records the sound of the objects shredding the ionosphere.

"Maybe somebody recorded this on surveillance camera. So if there's other videos, then we might be able to triangulate and see if there's a meteorite that landed somewhere," said Ashcraft.

Thomas says that this fireball was created by something about the size of a filing cabinet, but he can spot something as small as this bolt burning through the atmosphere.

Asteroid is Actually a Protoplanet: Study of First High-resolution Images of Pallas Confirms

ScienceDaily
Tue, 13 Oct 2009 12:40 EDT

© Science/AAAS
Pallas's largest crater-like feature seen in the digital model (left) and from two perspectives: appearing face-on (upper right) and edge-on along the limb (lower right).

Britney E. Schmidt, a UCLA doctoral student in the department of Earth and space sciences, wasn't sure what she'd glean from images of the asteroid Pallas taken by the Hubble Space Telescope. But she hoped to settle at least one burning question: Was Pallas, the second-largest asteroid, actually in that gray area between an asteroid and a small planet?

The answer, she found, was yes. Pallas, like its sister asteroids Ceres and Vesta, was that rare thing: an intact protoplanet.

"It was incredibly exciting to have this new perspective on an object that is really interesting and hadn't been observed by Hubble at high resolution," Schmidt said of the first high-resolution images of Pallas, which is believed to have been intact since its formation, most likely within a few million years of the birth of our solar system.

"We were trying to understand not only the object, but how the solar system formed," Schmidt said. "We think of these large asteroids not only as the building blocks of planets but as a chance to look at planet formation frozen in time."

The research appears Oct. 9 in the journal Science.

"To have the chance to use Hubble at all, and to see those images come back and understand automatically this could change what we think about this object - that was incredibly exciting to me," Schmidt said.

Pallas, which is named for the Greek goddess Pallas Athena, lies in the main asteroid belt between the orbits of Jupiter and Mars. Schmidt likens it to the size of Arizona, her home state. The massive body is unique, she said, partly because "its orbit is so much different from other asteroids. It's highly inclined."

Hubble had tried to snap pictures of the round-shaped body before but came up short. So when the space telescope took images again in September 2007, Schmidt and her colleagues had several goals.

"We wanted to learn about Pallas itself - what its shape is like, what its surface is like, does it have large impact craters, does it have significant topography," she said.

With the Hubble images, Schmidt and her colleagues were able to take new measurements of Pallas' size and shape. They were able to see that its surface has areas of dark and light, indicating that the water-rich body might have undergone an internal change in the same way planets do.

Pallas wasn't just a big rock made of hydrated silicate and ice, they found.

"That's what makes it more like a planet - the color variation and the round shape are very important as far as understanding, is this a dynamic object or has it been exactly the same since it's been formed?" Schmidt said. "We think it's probably a dynamic object."

For the first time, Schmidt and her colleagues also saw a large impact site on Pallas. They were unable to determine if it was a crater, but the depression did suggest something else important: that it could have led to Pallas' small family of asteroids orbiting in space.

"It's interesting, because there are very few large, intact asteroids left," Schmidt said. "There were probably many more. Most have been broken up completely. It's an interesting chance to almost look into the object, at the layer underneath. It's helping to unravel one of the big questions that we have about Pallas, why does it have this family?"

Schmidt's co-authors include Peter C. Thomas, a senior researcher at Cornell University; James Bauer, a researcher with the Jet Propulsion Laboratory; J.Y. Li, a postdoctoral student at the University of Maryland; Schmidt's Ph.D. adviser, UCLA professor of geophysics and space physics Christopher T. Russell; Andrew Rivkin, a researcher at Johns Hopkins University; Joel William Parker, a researcher at the Southwest Research Institute in Boulder, Colorado; Lucy McFadden, a faculty member at the University of Maryland; S. Alan Stern of the Southwest Research Institute; Max Mutchler, a researcher at the Space Telescope Sciences Institute; and Chris Radcliffe, a digital artist in Santa Monica.

"When people think of asteroids, they think of 'Star Wars' or of tiny little rocks floating through space," Schmidt said. "But some of these have been really physically dynamic. Around 5 million years after the formation of the solar system, Pallas was probably doing something kind of interesting."

Asteroid isn't just a dry heap of rubble

Rachel Courtland
New Scientist
Mon, 12 Oct 2009 14:29 EDT

© NASA/ESA/J. Parker/SWRI/P. Thomas/Cornell U/L. McFadden/University of Maryland/M. Mutchler/Z. Levay/STScI
The largest asteroid, Ceres (shown), appears to contain a lot of water ice beneath its surface. Now ice has been detected on the surface of the asteroid 24 Themis, which lies about three times as far from the sun as Earth does.

Two independent teams have found what may be the first direct evidence of water ice on the surface of an asteroid. The discovery lends support to the idea that asteroids could have helped deliver water to the early Earth.

Asteroids are generally considered to be rocky, and comets icy. That's because ice in the early solar system is thought to have formed beyond a "snow line" lying somewhere between Mars and Jupiter. Asteroids forming beyond that boundary could contain ice.

But it is not clear how common ice might be in the main asteroid belt, because sunlight is expected to quickly vaporise ice on the surfaces of airless bodies that fly closer to the sun than Jupiter.

In 2008, however, Andrew Rivkin of Johns Hopkins University in Laurel, Maryland, and Joshua Emery of the SETI Institute in Mountain View, California, found hints that the asteroid 24 Themis, which sits in the main asteroid belt between Mars and Jupiter, could have water ice on its surface. The team found the water signal by measuring the spectrum of infrared light radiated by the object.

Now a second team has found the water ice signature using the same telescope, NASA's Infrared Telescope Facility in Hawaii.

The new observations suggest water ice, mixed with organic molecules, is "widespread on the surface of the asteroid", Humberto Campins of the University of Central Florida in Orlando reported at a meeting of the American Astronomical Society's Division of Planetary Sciences in Fajardo, Puerto Rico, last week.

Icy parent

That is surprising, since the asteroid's distance from the sun means it should lose about 1 metre of ice each year. "This ice is unstable, and therefore we need a process to explain why there is ice on the surface now," Campins said at the meeting.

One possiblity is that an icy object might have collided with 24 Themis, leaving behind a layer of ice. Alternatively, the ice could have been part of the asteroid's parent body, which is thought to have broken up about 2.5 billion years ago, producing a family of asteroids with orbits similar to that of 24 Themis.

In that case, the ice seen on the surface now would once have been buried beneath dust and rock that insulated it from the sun's heat and prevented it from escaping into space. Impacts could then have churned the surface to expose the ice.

Watery hints

Until now, the possibility of present-day water ice on asteroids has only been hinted at. The density of the mammoth main-belt asteroid Ceres suggests it contains a large amount of water ice, but no clear-cut sign of ice has been found on its surface.

"This Themis result is really nice because it's been confirmed by two independent groups," says Henry Hsieh of Queen's University Belfast in the UK, though he notes that the spectral evidence for ice may not be entirely water-tight.

"It's a messy region [of the spectrum] that's hard to observe," says Clark Chapman of Southwest Research Institute in Boulder, Colorado. "In some sense, it's a matter of judgment whether it's a hint of water ice or an almost certain detection or somewhere in between."

Still, Chapman says, he would not be surprised to see water ice on asteroids, adding that the distinction between comets, traditionally considered to be icy, and asteroids, which have been largely thought of as rocky, is becoming increasingly blurred.

Comet tails

In recent years, Hsieh and others have discovered a handful of main-belt asteroids with comet-like tails that could be created by sublimating ice.

These so-called "main-belt comets" are too distant and faint for astronomers to scan their spectra for signs of water ice. Two of the four detected so far are part of the same family of asteroids as 24 Themis, which is the family's largest member.

"What is most likely the case is that the parent body [of this family] was water-ice-rich, was broken up, and now the surface of its largest fragment, Themis, has been impact-excavated, revealing the ice that was once deep in a larger object," says Britney Schmidt of UCLA, who was not affiliated with Campins's study. "It is exciting to finally get a glimpse inside a water-rich body."

Mismatched isotopes

David Jewitt of UCLA, co-discoverer of the first main-belt comets, agrees. "These objects may hold ice and preserve a record of conditions at formation between the orbits of Mars and Jupiter," he told New Scientist.

The detection could also go a long way towards explaining how the Earth got its water. Soon after the solar system's formation, the sun's heat is thought to have broken apart most water molecules that lay close to the sun.

Comets, which formed far from the sun, have been proposed as an alternate way of delivering water to the Earth, but the relative amounts of different isotopes of hydrogen in the water on comets do not match up with Earth's. "If there was water in the asteroids, it could be enough to fill the oceans," Hsieh says.

North America Comet Theory Questioned

Rex Dalton
Nature News
Mon, 12 Oct 2009 10:00 EDT

© Vance Holliday
Sediments at the San Jon site, in eastern New Mexico, contained very low abundances of magnetic spherules said to be evidence of an impact.

No evidence of an extraterrestrial impact 13,000 years ago, studies say.

An independent study has cast more doubt on a controversial theory that a comet exploded over icy North America nearly 13,000 years ago, wiping out the Clovis people and many of the continent's large animals.

Archaeologists have examined sediments at seven Clovis-age sites across the United States, and did not find enough magnetic cosmic debris to confirm that an extraterrestrial impact happened at that time, says the report in the Proceedings of the National Academy of Sciences (PNAS). It is the latest of several studies unable to support aspects of the impact hypothesis.

In 2007, a team led by Californian researchers announced a theory that a comet or asteroid had exploded over the North American ice sheet, creating widespread fire and an atmospheric soot burst followed by a cooling period known as the Younger Dryas.

Sometime after this, the Clovis people, sophisticated large-animal hunters known for their spear points, mysteriously disappeared; the team linked their vanishing to the environmental effects of the proposed impact.

Key evidence came in the form of magnetic microspherules discovered in sediments at 25 locations, including eight Clovis-age sites. Richard Firestone, of Lawrence Berkeley National Laboratory in California, and his colleagues argued that the microspherules were remnants of cosmic debris from an explosion.

But in more than 18 months of sedimentary analysis, a team led by Todd Surovell, an archaeologist at the University of Wyoming in Laramie, was unable to detect microspherule peaks. Two of the seven sites the group studied were places where Firestone's team identified spherule peaks.

"I spent hundreds of hours at the microscope examining sediment samples," says Surovell, "and I didn't find any physical evidence to support their theory."

Standing firm

The other team isn't backing down. "Their study doesn't negate our hypothesis," says James Kennett, a palaeoceanographer at the University of California at Santa Barbara and one of Firestone's co-authors. Another co-author, avocational geophysicist Allen West of Prescott, Arizona, says that Surovell's group didn't use the correct technique to extract, identify and quantify the microspherules.

Several other groups have been unable to support important aspects of the comet theory.

In a PNAS article published in February, Jennifer Marlon, a doctoral geography student at the University of Oregon in Eugene, and her colleagues found no systematic burning of biomass - as would have occurred if continent-wide fires had happened - at the time of the Younger Dryas in pollen and charcoal records at 35 sites. And at the Ecological Society of America meeting in Albuquerque, New Mexico, in August, Jacquelyn Gill, a palaeoecology doctoral student at the University of Wisconsin-Madison, reported finding no evidence of massive burning in sediment cores taken from lake beds in Ohio and Indiana.

Kennett, however, calls these studies "flawed". In August, his team published a report saying they had found nanometre-sized diamonds, purportedly created during an impact, and soot in sediments dated to the Younger Dryas on Santa Rosa Island, off the coast of California.

More studies of the theory - both critical and supportive - are in the publishing pipelines at other journals.

Surovell's co-author Vance Holliday, an archaeologist at the University of Arizona in Tucson, and his colleagues have an article in press at Current Anthropology that says the archaeological and geochronological records don't support a collapse of Clovis people at the time of the purported impact.

Comment: For a more in-depth view, read: The Younger Dryas Impact Event and the Cycles of Cosmic Catastrophes - Climate Scientists Awakening

What Hit Earth in 1908 with the Force of 3,000 Atomic Bombs?

PhysOrg
Tue, 13 Oct 2009 00:00 EDT

There have been numerous theories proposed about what struck the taiga in central Siberia, causing millions of trees to topple over and many still-standing trees to lose all their branches. Many expeditions have looked for traces of what hit Earth and have not found much. There is no telltale meteor crater, and no clear evidence of a nuclear blast. In fact, at the epicenter, the trees were found to be still standing. Whatever hit Earth did not reach the ground. It exploded in the air above the ground.

In The Tunguska Mystery by Vladimir Rubtsov, the efforts put forth by generations of Russian scientists, technicians, and others are documented. What did they find? Was it a meteorite, as had first been thought? Was it an asteroid? Was it a comet? Some support the idea that this was not a "natural" event at all but one caused by the explosion of an alien spaceship trying to land on Earth. Is there any evidence for this? How did the Russian scientific and world community react to this theory?

The mystery has been very difficult to solve, but it is important - perhaps even urgent - to solve it. We live in a very violent universe, and we are extremely vulnerable to its vagaries. How can we prevent another "Tunguska" if we don't even know what it was? And next time, the event might not occur in a remote, barely inhabited region of Earth. It may take many thousands of lives and destroy whole cities.

Vladimir Rubtsov was born in 1948 in Kharkov, Ukraine. He received his Ph.D. degree in the Philosophy of Science from the Institute of Philosophy of the Academy of Sciences of the USSR, having defended in 1980 the doctoral thesis: "Philosophical and Methodological Aspects of the Problem of Extraterrestrial Civilizations," the first of its kind in the former USSR. Dr. Rubtsov has authored two monographs and some 120 scientific and popular science articles in the Soviet, post-Soviet and international press.

Scientists May Have Found First Direct Evidence of Water Ice on Asteroid's Surface

Thaindian News
Tue, 13 Oct 2009 14:32 EDT

Two independent scientific teams have found what may be the first direct evidence of water ice on the surface of an asteroid, a discovery that lends support to the idea that asteroids could have helped deliver water to the early Earth.

Asteroids are generally considered to be rocky, and comets icy. That's because ice in the early solar system is thought to have formed beyond a "snow line" lying somewhere between Mars and Jupiter.

Asteroids forming beyond that boundary could contain ice.

But, it is not clear how common ice might be in the main asteroid belt, because sunlight is expected to quickly vaporise ice on the surfaces of airless bodies that fly closer to the sun than Jupiter.

In 2008, however, Andrew Rivkin of Johns Hopkins University in Laurel, Maryland, and Joshua Emery of the SETI Institute in Mountain View, California, found hints that the asteroid 24 Themis, which sits in the main asteroid belt between Mars and Jupiter, could have water ice on its surface.

The team found the water signal by measuring the spectrum of infrared light radiated by the object.

Now, according to a report in New Scientist, a second team has found the water ice signature using the same telescope, NASA's Infrared Telescope Facility in Hawaii.

The new observations suggest water ice, mixed with organic molecules, is "widespread on the surface of the asteroid," said Humberto Campins of the University of Central Florida in Orlando.

That is surprising, since the asteroid's distance from the sun means it should lose about 1 metre of ice each year.

"This ice is unstable, and therefore we need a process to explain why there is ice on the surface now," said Campins.

One possibility is that an icy object might have collided with 24 Themis, leaving behind a layer of ice.

Alternatively, the ice could have been part of the asteroid's parent body, which is thought to have broken up about 2.5 billion years ago, producing a family of asteroids with orbits similar to that of 24 Themis.

"What is most likely the case is that the parent body (of this family) was water-ice-rich, was broken up, and now the surface of its largest fragment, Themis, has been impact-excavated, revealing the ice that was once deep in a larger object," said Britney Schmidt of UCLA.

"It is exciting to finally get a glimpse inside a water-rich body," she added.

Hunting Arctic Asteroid Impact With Hovercraft

Alexis Madrigal
Wired
Mon, 12 Oct 2009 17:43 EDT

Two polar scientists hot on the trail of an arctic mystery have a new tool for exploration: a hovercraft, specially outfitted for week-long trips over the ice with scientific instruments and solar panels.

Their quarry is a nearly 22,000 square-mile patch of disturbed Arctic sea floor that could be evidence of a massive asteroid strike. John Hall, a now-retired geoscientist, discovered the anomaly during his late-'60s graduate work aboard Fletcher's Ice Island, a huge berg U.S. scientists inhabited for several decades.

Since then, no scientific vessel has been back over the area to collect more data. The massive icebreakers that have crunched through the Arctic since the 1990s can't reach the spot, said Yngve Kristofferson, a scientist and explorer at the University of Bergen in Norway.

Kristofferson became intrigued with Hall's data and in 2004, the two of them met in Bergen to talk Arctic science from eight in the morning to 10 in the evening. At the end of their time together, they came to a decision: They needed a hovercraft.

Luckily, Hall is a partial heir to the fortune his grandfather made as head of the American Chicle Company, the trust that ran the American bubble gum game early in the 20th century, so he was able to buy the vehicle with private funds. A customized Griffon Hovercraft 2000TD, it is now going through the paces, hitting the Arctic from its home at Longyearbyen for the first time in 2008, and hoping to reach its full potential next spring.

Hall delivered a speech detailing the craft's capabilities and mission at Columbia University's Lamont Doherty Earth Observatory on Oct. 6.

"The neat thing with a hovercraft is that you drive with the same ease over 10 centimeter-thick ice as you do with five meter thick ice," Kristofferson told Wired.com.

Despite their futuristic reputation, hovercraft have been commercially available for decades. The concept is actually quite simple. A big engine or turbine pumps air into a rubber skirt that allows the vehicle to tread lightly on whatever it's touching. The R/H Sabvabaa, for example, weighs six tons but exerts no more pressure on any patch of ice than a seagull standing on one leg would by standing on it. The rest of the power from the engine is devoted to propulsion, allowing the craft to skip along at speeds up to 50 miles per hour.

For the strange terrain of the Arctic, it works perfectly, Hall and Kristofferson wrote in an article in the journal The Leading Edge in August.

"The craft has proved to be useful for a variety of scientific tasks," they wrote. "It appears more efficient than any other platform for ice-thickness measurements and oceanographic work."

Their hovercraft push comes as money has flooded into Arctic research. With Arctic ice melting, the nations adjacent to the ocean are rushing to stake their claims not just on the water, but on the oil and natural gas that lie under the sea floor, leading to calls to establish a National Park to protect the area.

The most fascinating target for the hovercraft is the area of very thick ice closer to Ellesmere Island and northern Greenland. Not even nuclear-powered icebreakers have ventured into the region. It was just Hall's good fortune to have been aboard the floating ice island doing research when it passed near this apparent sea floor anomaly. The duo, along with several other colleagues, described the discovery in a 2008 paper in the Norwegian Journal of Geology.

"The upper couple hundred meters of sediment at the bottom of the Arctic Ocean is just like a carpet that is draped over the topography except for these areas where 150 meters are just blown away and the seabed is severely deformed," Kristofferson said.

To Kristofferson and Hall, the evidence suggests that a pressure wave caused by a pieces of a large asteroid crashing into the Arctic Ocean created these strange features.

"Our working hypothesis is that the spectrum and scale of the observed disturbances are best explained as the effect of a shock wave generated by the impact of an extraterrestrial object," they wrote.

But the hypothesis remains just that without more data. The hovercraft works well, but with its on-board fuel, its range is limited to around 500 miles. For that reason, the scientists imagine they'll use a larger vessel as a base of operations.

"What we really want to do is go along with an icebreaker into the Arctic. You can greatly enhance the scientific output if you have a hovercraft. If you have more of them, even better," Kristofferson said. "We can go out and do our own science and be away for many days. If the icebreaker gets stuck, we're not stuck."

Still, both Hall and Kristofferson know they face an uphill battle to get other scientists to take both the hovercraft and asteroid impact ideas seriously.

"The task is to figure out the real message in the data - the dream challenge for any scientist," Kristofferson told the Lamont Doherty alumni magazine earlier this year. "So far, we have mostly met shaking heads, which just makes it more fun."

Meteor explodes over Groningen, Netherlands: Fireball seen from Belgium and Germany

Dutch News
Wed, 14 Oct 2009 16:51 EDT

Hundreds of people report seeing a spectacular fireball or meteorite over the Netherlands in Tuesday's clear evening skies.

The police emergency number, Dutch coastguard and KNMI weather bureau report dozens of phone calls about the meteorite, which was seen in Germany and Belgium.

'I was standing in front of my window when there was a bright flash of light and a white fireball in the sky fell apart into three smaller ones,' eyewitness Erik Alberts from Zuidbroek in Groningen province told Nos tv. 'Like fireworks. A few seconds later, perhaps half a minute, there was a low rumble and the windows shook.'

Astronomers digging for meteors in Grimsby, Western Ontario

Peter Downs
The Tribune / Sun Media
Wed, 07 Oct 2009 22:02 EDT

© University of Western Ontario
A composite photograph of the meteor that streaked across southern Ontario Sept. 25. It is believed meteorites landed in the Grimsby area.

Space rocks formed when the solar system was created billions of years ago are believed to have fallen to Earth near Grimsby in a fiery light show two weeks ago.

Astronomers will be digging through farmers' fields Thursday and Friday on the hunt for hunks of a meteor that blazed across the skies of southern Ontario Sept. 25 shortly after 9 p.m.

The beachball-sized meteor was first picked up by cameras operated by the University of Western Ontario's physics and astronomy department 100 kilometres above Guelph as the fireball streaked southeastward at a speed of about 75,000 km/h.

Astronomers at the university have traced the meteor's path and believe chunks of it may have landed above the escarpment within a 10-km radius of Grimsby.

"We're pretty certain something came down," said Phil McCausland, a postdoctoral fellow with the university's astronomy department.

"It's hard to put an X on the map and say, 'There,' because what happens is at the end of the fireball path the lights go out. There's no camera record of that."

It's likely small pieces of the meteor - anywhere between the size of a golf ball or a fist - made it through the atmosphere and hit the ground, he said.

"It could be dozens, it could be one or two. It's hard to say, but if it's one or two, they will be on the largish size - probably more than a kilogram."

Researchers are keen to find any of the meteorites because it's extremely rare to have their fall to Earth documented so well with photo evidence.

Based on all of the information already known about the rocks, it's possible for astronomers to determine which orbit they came from and learn more about the early history of the solar system.

"There's only a handful, perhaps a dozen, meteorites that have this kind of orbital information," McCausland said.

The rural area where the meteorites are believed to have landed is largely farmland with some forest.

McCausland has already spent several days over the past week searching for the rocks and interviewing landowners in the area.

He was expected to be back on the hunt again Thursday with other researchers.

"Even though the (cameras) we have narrows it down quite nicely, it's still a large area to search. We're still talking about 12 to 16 kilometres," he said.

Doug Welch, an astrophysicist at McMaster University, will be joining the search.

Welch monitors one of Western's meteor-seeking sky cameras at the Hamilton university.

The fireball that torched across the sky two weeks ago practically went directly overhead of the Hamilton camera.

"It's really spectacular. ... I've seen them live, but it's very rare for them to be this bright," he said.

Recovering meteorites that may have fallen gives researchers a rare opportunity to learn more about the formation of the solar system, he said.

"These are free samples from elsewhere in the solar system delivered to your door. We have sample-return missions that cost hundreds of millions of dollars."

Meteorologist and Grimsby resident Kerry-Ann Lecky Hepburn spends much of her spare time photographing the stars and planets.

But the night the fireball streaked towards Grimsby, she didn't have her camera trained on the sky. She was watching TV with her meteorologist husband in their home atop the escarpment.

"We saw a bright flash and thought, 'How can it be a thunderstorm. There shouldn't be any storms around.'"

A quick check online the following morning confirmed for Lecky Hepburn the bright light was a meteor.

"It would have been nice to see something other than just the bright flash," she said.

Researchers are calling for anyone who has found pieces of meteorite to contact them, as well as people in the area who witnessed the fireball.

Meteorites are typically dark, smooth on the surface, heavier than rocks of a similar size and able to attract magnets because of the metals they contain.

Under Canadian law, meteorites become the property of whoever owns the property where they are recovered.

Photos and video footage of the meteor can be found online.

Canada, Ontario: Grimsby meteorite found

The Standard
Thu, 15 Oct 2009 17:00 EDT

The Grimsby space rock has been found.

A fragment of meteorite the size of a golf ball smashed in the windshield of a Grimsby family's sport utility vehicle on Sept. 25, according to a media release from the University of Western Ontario.

Astronomers released a video Oct. 7 of a blinding meteor streaking across the skies of Southern Ontario three weeks ago, estimating pieces may have landed in Grimsby or West Lincoln.

Meteorite hunters have been scouring the area ever since.

A press conference to discuss the find is scheduled for Friday morning.

US: Meteorite streaks across New Mexico sky

Gadi Schwartz and Matthew Kappus
KOB.com
Mon, 12 Oct 2009 17:20 EDT

Scientists think a fireball that flew over New Mexico may have been close enough to actually hit the ground.

A Santa Fe astronomer was able to catch the fiery streak on video. Thomas Ashcraft says the fireball didn't disintegrate when it hit the atmosphere. It may have landed somewhere near Taos.

"If we can get other camera angles, than we can put all the positions together and possibly hunt for an important--scientifically important--meteorite," he said.

The event was also captured by cameras at Sandia National Labs. Scientists estimate the meteor was about the size of a basketball all the way up to that of a small car.

Scientists at Sandia think it disintegrated over Chaco Canyon.

Giant Impact Near India - Not Mexico - May Have Doomed Dinosaurs

ScienceDaily
Thu, 15 Oct 2009 05:00 EDT

A mysterious basin off the coast of India could be the largest, multi-ringed impact crater the world has ever seen. And if a new study is right, it may have been responsible for killing the dinosaurs off 65 million years ago.

© Geological Society Of America
Three-dimensional reconstruction of the submerged Shiva crater (~500 km diameter) at the Mumbai Offshore Basin, western shelf of India from different cross-sectional and geophysical data.

Sankar Chatterjee of Texas Tech University and a team of researchers took a close look at the massive Shiva basin, a submerged depression west of India that is intensely mined for its oil and gas resources. Some complex craters are among the most productive hydrocarbon sites on the planet. Chatterjee will present his research at this month's Annual Meeting of the Geological Society of America in Portland, Oregon.

"If we are right, this is the largest crater known on our planet," Chatterjee said. "A bolide of this size, perhaps 40 kilometers (25 miles) in diameter creates its own tectonics."

By contrast, the object that struck the Yucatan Peninsula, and is commonly thought to have killed the dinosaurs was between 8 and 10 kilometers (5 and 6.2 miles) wide.

It's hard to imagine such a cataclysm. But if the team is right, the Shiva impact vaporized Earth's crust at the point of collision, leaving nothing but ultra-hot mantle material to well up in its place. It is likely that the impact enhanced the nearby Deccan Traps volcanic eruptions that covered much of western India. What's more, the impact broke the Seychelles islands off of the Indian tectonic plate, and sent them drifting toward Africa.

The geological evidence is dramatic. Shiva's outer rim forms a rough, faulted ring some 500 kilometers in diameter, encircling the central peak, known as the Bombay High, which would be 3 miles tall from the ocean floor (about the height of Mount McKinley). Most of the crater lies submerged on India's continental shelf, but where it does come ashore it is marked by tall cliffs, active faults and hot springs. The impact appears to have sheared or destroyed much of the 30-mile-thick granite layer in the western coast of India.

The team hopes to go India later this year to examine rocks drill from the center of the putative crater for clues that would prove the strange basin was formed by a gigantic impact.

"Rocks from the bottom of the crater will tell us the telltale sign of the impact event from shattered and melted target rocks. And we want to see if there are breccias, shocked quartz, and an iridium anomaly," Chatterjee said. Asteroids are rich in iridium, and such anomalies are thought of as the fingerprint of an impact.

Mars Rover Spots Another Meteorite

Space.com
Mon, 12 Oct 2009 17:10 EDT

NASA's intrepid Mars rover Opportunity has found yet another meteorite on the surface of the red planet.

Opportunity stumbled upon this new meteorite, dubbed "Shelter Island," less than three weeks after driving away from a larger meteorite that the rover examined for six weeks.

The rover began its approach to the meteorite with a 92-foot (28-meter) backwards drive on Oct. 1, the rover's 2,022nd day on Mars.

Opportunity and its twin rover Spirit - which is currently embedded in a soft spot of soil called Troy - have been on the Martian surface for more than five years.

Shelter Island is a pitted rock is about 18.5 inches (47 cm) long. The meteorite was first detected in images taken two Martian days earlier. (A Martian day is 24 hours and 40 minutes long.)

Two Martian days after its backward drive, Opportunity turned around to face the meteorite. In the days that followed, it made a final 3.3-foot (1-meter) move to put the rock within reach of the rover robotic arm . Mission managers are now planning to use the arm to contact the meteorite and make measurements.

Opportunity has driven about 2,300 feet (700 meters) since it finished studying the meteorite called "Block Island" on Sept. 11, 2009.

Block Island weighs at least half a ton, is composed of iron and nickel, and is likely too large to have plunged through the current thin atmosphere of Mars without being obliterated upon impact, scientists say.

Both meteorites have been found during Opportunity's trek to its next target, Endeavour Crater.

Opportunity also found a third meteorite, Heat Shield Rock, in 2004.

Video: Grimsby, Ontario meteor 25 September

TheSpec.com
Fri, 16 Oct 2009 10:41 EDT

Comment: You can read a report of this sighting here

UK: Red-hot piece of "space junk" crashes through pensioner's roof

The Daily Mail
Fri, 16 Oct 2009 10:43 EDT

Pensioner Peter Welton was amazed when a piece of red-hot debris crashed through his roof in July. Now experts have confirmed the object had travelled hundreds of miles from outer space.

The 75-year-old had been in his bedroom when he heard a smash and found the football-sized lump of extra terrestrial debris in the loft of his home in Hull.

The great-grandfather said: 'It was a hell of a shock. If it had landed in the street and hit anybody it would have killed them.'

As it was too hot to handle he brought it downstairs using oven gloves.

The 4lb dark grey object was removed by Humberside Police before being taken away by the Ministry of Defence for investigation.

Mr Welton and wife Mair, 62, then received a phone call from the RAF, who said the metal mass was most likely to be space junk. This could mean anything from part of a spacecraft to a piece of abandoned satellite.

Comment: And how about a meteorite? After all, considering the increasing frequency of 'falling rocks' reports, they are past due to be incorporated into daily weather forecasts.

RAF spokesman Squadron Leader Jeff Brock confirmed the finding, which was the first the RAF's Defence Flying Complaints Investigation Team had encountered.

He said: 'Following consultations with the European Space Agency and Nasa, we are confident the object is more than likely space debris which was orbiting in excess of a decade.

'This is the first bit of space debris that we have got our hands on - we have never until this occasion had anything relating to it at all.'

The DFCIT, based in Henlow, in Bedfordshire, investigates complaints related to military flying. Experts initially thought the object may have come from an aircraft.

However, its size and appearance was found to be 'entirely consistent' with space junk, and its heavy mass meant it was more likely to have been in a state of decaying orbit for a decade or more.

Russia (then the Soviet Union) put the first object into space just 51 years ago - Sputnik One. Since then we have created a swarm of perhaps tens of millions of items of space junk. The debris ranges in size from paint flecks to defunct satellites.

The oldest piece of space junk still circling is the Vanguard 1 communications satellite that was launched by the U.S in 1958, but stopped working in 1964.

Most hug close to the surface, 200-300 miles up in low-earth-orbit, where they are a hazard to telescopes and the astronauts on the International Space Station.

Most debris will eventually burn up in the atmosphere, but larger objects can reach the ground intact. Most have come down over the Pacific Ocean or sparsely populated areas.

There has only been one recorded incident of a person being hit by human-made space debris. In 1997, Lottie Williams from Oklahoma was hit in the shoulder by a 5.1" piece of blackened metal. It was later confirmed to be part of the a rocket fuel tank launched the year before. Luckily she was not injured.

Despite narrowly escaping being hit, Mrs Mair said she was excited to hear the experts' findings.

'I think it's wonderful,' she said.

Mail's online video report on the event

Canada, Ontario: Small meteorite broke windshield of SUV

Mark McNeil
The Hamilton Spectator
Fri, 16 Oct 2009 11:36 EDT

Scientists say a golf ball-sized rock that smashed through the windshield of an SUV is a meteorite, possibly from a spectacular fireball that streaked across the sky above Hamilton three weeks ago.

University of Western Ontario researchers confirmed the rock was a meteorite. It will be unveiled today at a media conference.

The fireball was captured on video Sept. 25 by a network of cameras administered by Western that regularly watch the skies at night. One of the cameras is located at McMaster University.

For the past two weeks, a search team headed by Phil McCausland, a postdoctoral fellow at Western's Centre for Planetary Science and Exploration, has been scouring the Grimsby area after working out mathematical models that suggest the fireball crashed there.

McCausland believes there are other meteorites on the ground that have yet to be found because the meteor weighed as much as a tonne when it hit Earth's atmosphere.

He returned to Grimsby yesterday with a search team of a few people looking around the residential area where the meteorite was discovered by a Grimsby resident.

"It was a very unusual rock, so the finder just held onto it," McCausland said. "They began to think it was a meteorite after the media coverage happened."

He would not be specific about where the rock was located, only that it was "just barely" within the 12-square-kilometre area south of the town of Grimsby that searchers were focusing on.

Tests are being done to try to find out more about the 50-gram object.

The discovery, he said, has buoyed enthusiasm that other pieces will be found and it will turn out to be a major find for the astronomy community.

Meteorites are relatively common, but it is highly unusual to find one from a meteor videotaped coming through the atmosphere.

"You don't stop when you find one piece. You keep going," said McCausland. "Finding one is confirmation that something came down here and there are probably many others."

They are looking intensively in the area of the first find because "meteorites don't care where they land. They could hit a house, a roof. They can end up anywhere."

mmcneil@thespec.com

905-526-4687

Hundreds See 'Exploding Fireball' in Sky

Trak.in News/Asian News International
Mon, 19 Oct 2009 00:00 EDT

Washington - Reports indicate that hundreds of people in the Netherlands and Germany have reported seeing a huge exploding fireball in the sky on October 13.

According to a report in National Geographic News, amateur photographer Robert Mikaelyan captured the phenomenon on camera.

Mikaelyan managed to capture several shots of the fireball as it swung low over the northern city of Groningen, Netherlands, and began to break apart into smaller chunks.

"I suddenly saw a light in the sky coming fast and quickly got the pictures taken," Mikaelyan said.

A few seconds after the fireball had been sighted, witnesses heard a sonic boom followed by low rumbles that rattled windows-signatures of a high-altitude explosion.

The object was most likely a rogue space rock that disintegrated shortly after hitting Earth's atmosphere, according to experts, who speculate that pieces of the meteor may have landed in the North Sea.

"Indeed it was a huge event," said Theo Jurriens, of the Kapteyn Astronomical Institute at the University of Groningen.

Earth is constantly being bombarded by smaller debris from comets, asteroids, and even other rocky planets in the solar system.

But a fireball of this size and brightness is likely seen anywhere in the world only every 20 to 25 years, according to Jurriens.

Comment: Every 20-25 years? Somebody's not been paying attention. These are from the past 3 weeks:

October 9th: Caught on camera: Meteorite streaks across New Mexico sky

October 5th: Video: Fireball lights up sky over Iceland

Septmber 28th: Cosmic shock and awe: Fireball explodes over Argentina

September 25th: Spectacular Fireball filmed over Canada

Taiwanese amateur astronomer discovers new asteroid

Cheng Chi-feng and Sofia Wu
Central News Agency
Mon, 19 Oct 2009 19:05 EDT

Kaohsiung - An amateur astronomer who discovered an asteroid earlier this year presented a model of his new discovery to Kaohsiung Mayor Chen Chu Monday to share it with all residents of the southern Taiwan port city.

Tsai Yuan-sheng discovered the asteroid along with an assistant at the Lulin Observatory on Yushan, also known as Jade Mountain, March 20 and tentatively named it "Kaohsiung" after his hometown.

In August, the International Astronomical Union's Committee on Small Body Nomenclature (IAU's CSBN) -- an international organization responsible for the naming of asteroids and comets -- formally approved the designation and gave Tsai's discovery a permanent number "215080." It was the first asteroid discovered by an amateur Taiwanese astronomy buff to have won international recognition.

The asteroid, located between Mars and Jupiter, is similar in size to Kaohsiung International Airport. At perihelion, the closest point to the sun in its orbit, the asteroid is 350 million kilometers from the sun and at aphelion, its most distant point from the sun in its orbit, it is about 450 million kilometers from the sun.

It takes about four years for the newly identified asteroid to complete its orbit around the sun.

Tsai and Lin Chi-sheng, an astronomical observation assistant at Lulin Observatory, spotted the asteroid using highly advanced digital equipment.

Tsai recalled that he first detected that the body could both rotate around its own axis and circle the Sun and that its position coordinates varied each day.

"I then took photos of the object consecutively for analytical comparison and finally came to the conclusion that it was an asteroid that had never been documented before," Tsai recalled.

According to Tsai, most larger asteroids have been discovered and only small asteroids that cannot be detected with the naked eye are still left to be spotted with highly sophisticated instruments.

Tsai, 40, began to develop his interest in observing the stars while studying at a military preparatory school as a teenager. At the time, he was required to stand guard at night, and the long hours with nothing to do led him to fall in love with stargazing.

He later dropped out of the naval academy to pursue his hobby more freely. He now often takes his wife and children high into the mountains to observe the stars at night.

Tsai has documented 13 asteroids, but "Kaohsiung" is the only one to have been recognized by the IAU's CSBN.

"I was so jubilant to obtain international recognition of my latest discovery and thus decided to name it 'Kaohsiung' to honor my beloved homeland," Tsai said.

"I also want to share my happiness in discovering the new body with all fellow Kaohsiung residents, " Tsai said at the asteroid model presentation ceremony at the city's Gangho Elementary School.

For her part, Mayor Chen said the discovery of the asteroid and its designation as "Kaohsiung" are not only the "pride of Kaohsiung" but also the "pride of Taiwan." Noting that Tsai's achievement has inspired a "star chasing" fad in the city, Chen said the city government will step up efforts to promote astronomical education and cultivate more talent in the field.

Chen said she has directed the city's Bureau of Education to allocate NT$1 million (US$31,056) annually to help finance the operations of the Gangho Elementary School's astronomy observatory.

She also proposed that an astronomy-themed science park be established after Kaohsiung City and Kaohsiung County merge next year.

Tsai Ching-hua, director of the municipal education bureau, said the discovery of the asteroid has set a good model for the city's astronomy education and pledged to study the feasibility of setting up an astronomy theme park in the new Kaohsiung municipality.

Orionid Meteor Shower

Space Weather
Tue, 20 Oct 2009 15:16 EDT

The Orionid meteor shower is underway. Earth is passing through a stream of dusty debris from Halley's Comet, and this is causing meteors to shoot out of the constellation Orion. Earlier today, amateur astronomer Jefferson Teng photographed an Orionid fireball over Shanghai, China.

"I woke up early in the morning to observe the shower through my bedroom window," says Teng. "This one was quite bright considering the light pollution in Shanghai."

Forecasters expect the shower to peak on Wednesday, Oct. 21st, with dozens of meteors per hour. The best time to look is during the dark hours before sunrise. For best results, get away from city lights, but as Teng discovered, country darkness is not absolutely necessary.

Did a meteor make this crater in Latvia?

Associated Press
Mon, 26 Oct 2009 10:07 EDT

Investigators Say Radiation Levels Normal

Scientists were investigating Monday whether a large crater found in a meadow in northern Latvia had been created by meteorite. One expert said it was likely a hoax.

Experts in the Baltic country rushed to the site after reports that a metorite-like object had crashed late Sunday in the Mazsalaca region near the Estonian border.

Uldis Nulle, a scientist at the Latvian Environment, Geology and Meteorology Center, said his first impression after observing the site late Sunday was that the 27-foot (nine-meter) wide and nine foot (three-meter) deep crater had been caused by a meteorite. He said there was smoke coming out of the hole when he arrived.

However, Dainis Ozols, a nature conservationist who examined the hole in daylight on Monday, said it appeared to be a hoax. Ozols said he believes someone dug the hole and tried to make it look like a meteorite crater by burning some pyrotechnic compound at the bottom. He added he would analyze some samples taken from the site.

When asked about Ozols' theory, Nulle refused to comment, saying he needed more time to make tests at the site.

Inga Vetere of the Fire and Rescue Service said they received a call about the alleged meteorite on Sunday evening from an eyewitness. She said a military unit was dispatched to the site and found that radiation levels were normal. There were no injures.

Experts outside Latvia said it would be unusual for such a large meteorite to hit the Earth. The planet is constantly bombarded with objects from outer space, but most burn up in the atmosphere and never reach the surface.

In 2007, a meteorite crashed near Lake Titicaca in Peru, causing a crater about 40 feet (12 meters) wide and 15 feet (five meters) deep.

Asta Pellinen-Wannberg, a meteorite expert at the Swedish Institute of Space Research, said she didn't know the details of the Latvian incident, but that a rock would have to be at least three feet (one meter) in diameter to create a hole that size.

Henning Haack, a lecturer at Copenhagen University's Geological Museum said more information was needed to confirm that the crater was indeed caused by a meteorite.

"With all these kind of reports we get there always is a pretty large margin of error," he said.

Hoax? Video footage of blazing 'meteorite' in Latvia

Daily Mail
Mon, 26 Oct 2009 10:14 EDT

A fiery object struck farmland creating a large crater near a small town in northern Latvia.

No-one was injured in the incident and geologists are now studying the object, which may be a meteorite.

Locals claimed the object fell near a farmhouse on the outskirts of Mazsalaca town in the district of Valmiera last night.

It created a crater which measured 50 feet across and 16 feet deep.

A witness who claimed to have seen the incident described the 'meteorite' as making a noise similar to the one of an aircraft flying at a low altitude.

ldis Nulle, a scientist at the Latvian Environment, Geology and Meteorology Center, said there was smoke coming out of the crater when he arrived at the crash site late Sunday in the Mazsalaca region near the Estonian border.

'My first impression is that, yes, it was a meteorite,' he said. 'All the evidence suggests this when compared to pictures of real meteorite craters.'

He said the rim of the crater was slightly raised and there was a black-grayish scar at the bottom - both signs of a meteorite impact.

Experts outside Latvia said it was unusual for such a large meteorite to hit the Earth. The planet is constantly bombarded with objects from outer space, but most burn up in the atmosphere and never reach the surface.

In 2007, a meteorite crashed near Lake Titicaca in Peru, causing a crater about 40 feet (12 metres) wide and 15 feet (5 metres) deep.

Asta Pellinen-Wannberg, a meteorite expert at the Swedish Institute of Space Research, said she didn't know the details of the Latvian incident, but that a rock would have to be at least three feet (one metre) in diameter to create a hole that size.

Henning Haack, a lecturer at Copenhagen University's Geological Museum said more information was needed to confirm that the crater was indeed caused by a meteorite.

'With all these kind of reports we get there always is a pretty large margin of error,' he said.

In Latvia, Nulle said a group of experts would examine the crater today and bring rock samples back to the capital, Riga, for testing.

Nulle rushed to the site after people in the area reported seeing a fiery object falling from the sky.

Inga Vetere of the Fire and Rescue Service said a military unit has tested the site and found that radiation levels are normal. There were no injures.

She said police have cordoned off the area to prevent souvenir hunters from taking away the soil.

'We are not finally sure that this is a meteorite,' she told Itar-Tass news agency. 'Eyewitnesses said something fell from the sky and fire started.'

Russian blogs posted YouTube video that claimed to show the remains of the meteor burning brightly shortly after the crash, but the validity of the video has not yet been confirmed.

Meteorite falls in northern Latvia, no one injured

RIA Novosti
Mon, 26 Oct 2009 10:59 EDT

No one was injured after a meteorite fell near a small town in northern Latvia on Sunday, local Latvian media reported.

According to media reports, the meteorite fell near a residential house on the outskirts of Mazsalaca town in the Valmiera district of Latvia, leaving a crater of some 20 meters (66 feet) in diameter and 10 meters (33 feet) deep.

A spokesperson for the Latvian State Fire and Rescue Service said that rescuers and soldiers immediately cordoned off the territory, however, it is still not clear whether it was an asteroid or a space satellite.

"The territory has been immediately cordoned off as we still do not know what fell down from the sky. According to preliminary information, it was a meteorite. However, it is possible that it was a [space] satellite or its fragment. A radioactive contamination is also possible," she said.

A witness, who saw the object falling from the sky and leaving a burning trace behind, said it was making a noise similar to the one of an aircraft flying at a low altitude.

On March 2 this year, a 35-meter asteroid came within 72,000 kilometers of Earth. The size of the space rock was comparable to the asteroid that caused the Tunguska disaster, but there was no danger of a collision.

On June 30, 1908, an explosion equivalent to between 5 and 30 megatons of TNT occurred near the Podkamennaya Tunguska River in a remote region of Russia's Siberia.

The Tunguska blast flattened 80 million trees, destroying an area of around 2,150 sq km (830 sq miles).

It is assumed that a huge meteorite had hit the area, although research expeditions failed to find an obvious crater.

Comment: Update: This incident appears to have been staged

'Meteorite' that landed in Latvia is a hoax, experts say

'Meteorite' that landed in Latvia is a hoax, experts say

Tony Halpin
Times Online
Mon, 26 Oct 2009 18:09 EDT

It was the student prank that apparently fell to earth after experts dismissed a meteorite crash in Latvia as an elaborate hoax today.

Dramatic video of a fireball at the bottom of an impact crater on farmland outside the town of Mazsalaca was shown all over the world, taken by a group of film students who said that they had heard the meteor strike.

But experts who examined the scene were less star-struck. Dr Ilgonis Vilks, chairman of the scientific council at the University of Latvia's Institute of Astronomy, said: "It's a fake. It's very disappointing, I was full of hope coming here, but I am certain it is not a meteorite."

Setting aside the astronomical odds of a group of film students happening to be at the ready when a meteorite hits the Earth, Dr Vilks said that several other tell-tale signs had given the game away.

There was green grass inside the crater despite the intense heat supposedly generated by the meteorite. The impact crater, initially reported as 10 metres deep, was actually only 3 metres including a lip of soil a metre high around the hole.

Dr Vilks said that there was neither ejected material from the hole nor any fragments of meteorite on the surrounding land. Finally, there was the flaming "meteorite" itself.

"It's a ball of clay that was burning. We took some samples from it and geologists from the university will examine it," Dr Vilks said. "There was a small blast heard by local people but this was not strong enough to create the crater and there's only a small area in the hole that is burnt."

Dainis Ozols, a nature conservationist who also examined the scene, said that he believed somebody had dug the hole and burnt a pyrotechnic compound at the bottom to make it appear like a meteorite crater.

The alert was first raised on Sunday evening by Ancis Steinbergs, who said that he had been out filming for a university project with his girlfriend and a fellow undergraduate. He was refusing to answer his telephone tonight to answer questions about the experts' assessments.

He had earlier told The Times that the trio had heard a loud roaring sound "like an airplane falling from the sky" seconds before the alleged meteorite hit the field behind some trees.

Mr Steinbergs said: "We saw something burning in the sky like a ball and it was moving very fast and then there was a loud noise. We went to find it and there was this big hole with fire burning in it.

"It was so hot that the camera was misting up. We thought it was really dangerous because there might be an explosion."

Video taken by the group showed them approaching the lip of the crater and filming the glowing hot "meteor" at the bottom as they talked excitedly among themselves. The clip bears similarities in style to the Blair Witch Project, a 1999 film based on supposedly "amateur" footage shot by three missing film students.

Mr Steinbergs said that he called Latvia's Fire and Rescue Service. Inga Vetere, a spokeswoman, said that fire crews had attended the site and cordoned it off. Tests had recorded normal levels of radiation and nobody had been hurt.

Local news agencies reported that the landowner, Larisa Gerasimova, had been quick to capitalise on interest surrounding the crater and had begun to charge curious visitors $2 to view the site.

Earth is bombarded by thousands of small celestial objects every year but most burn up in the atmosphere before they reach the surface. The last recorded meteorite strike on land was in 2007 near Lake Titicaca in Peru, when it left a crater 12 metres wide (40ft) and five metres deep (15ft).

Asteroid blast reveals holes in Earth's defences

David Shiga
New Scientist
Tue, 27 Oct 2009 00:04 EDT

As the US government ponders a strategy to deal with threatening asteroids, a dramatic explosion over Indonesia has underscored how blind we still are to hurtling space rocks.

On 8 October an asteroid detonated high in the atmosphere above South Sulawesi, Indonesia, releasing about as much energy as 50,000 tons of TNT, according to a NASA estimate released on Friday. That's about three times more powerful than the atomic bomb that levelled Hiroshima, making it one of the largest asteroid explosions ever observed.

However, the blast caused no damage on the ground because of the high altitude, 15 to 20 kilometres above Earth's surface, says astronomer Peter Brown of the University of Western Ontario (UWO), Canada.

Brown and Elizabeth Silber, also of UWO, estimated the explosion energy from infrasound waves that rippled halfway around the world and were recorded by an international network of instruments that listens for nuclear explosions.

The explosion was heard by witnesses in Indonesia. Video images of the sky following the event show a dust trail characteristic of an exploding asteroid.

Sudden impact

The amount of energy released suggests the object was about 10 metres across, the researchers say. Such objects are thought to hit Earth about once per decade.

No telescope spotted the asteroid ahead of its impact. That is not surprising, given that only a tiny fraction of asteroids smaller than 100 metres across have been catalogued, says Tim Spahr, director of the Minor Planet Center in Cambridge, Massachusetts. Yet objects as small as 20 or 30 metres across may be capable of doing damage on the ground, he says.

"If you want to find the smallest objects you have to build more, larger telescopes," says Spahr. "A survey that finds all of the 20-metre objects will cost probably multiple billions of dollars."

The White House must develop a policy to address the asteroid hazard by October 2010 under a deadline imposed by Congress. It is likely to be influenced by a report from the National Research Council on the asteroid problem, which is expected by year's end.

Asteroid explosion over Indonesia raises fears about Earth's defences

Tom Chivers

Telegraph.co.uk
Tue, 27 Oct 2009 07:21 EDT

Comment: Benda Mirip Meteor Jatuh di Bone, Sulawesi Utara, October 8, 2009

An asteroid that exploded in the Earth's atmosphere with the energy of three Hiroshima bombs this month has reignited fears about our planet's defences against space impacts.

On 8 October, the rock crashed into the atmosphere above South Sulawesi, Indonesia. The blast was heard by monitoring stations 10,000 miles away, according to a report by scientists at the University of Western Ontario.

Scientists are concerned that it was not spotted by any telescopes, and that had it been larger it could have caused a disaster.

The asteroid, estimated to have been around 10 metres (30ft) across, hit the atmosphere at an estimated 45,000mph. The sudden deceleration caused it to heat up rapidly and explode with the force of 50,000 tons of TNT.

Luckily, due to the height of the explosion - estimated at between 15 and 20 km (nine to 12 miles) above sea level - no damage was caused on the ground.

However, if the object had been slightly larger - 20 to 30 metres (60 to 90ft) across - it could easily have caused extensive damage and loss of life, say researchers.

Very few objects smaller than 100 meters (300ft) across have been spotted and catalogued by astronomers.

Tim Spahr, director of the Minor Planet Center in Cambridge, Massachusetts, warned that it was inevitable that minor asteroids would go unnoticed. He said: "If you want to find the smallest objects you have to build more, larger telescopes.

"A survey that finds all of the 20-metre objects will cost probably multiple billions of dollars."

The fireball was spotted by locals in Indonesia, and a YouTube video taken that day "appears to show a large dust cloud consistent with a bright, daylight fireball", according to the Ontario researchers.

An asteroid or comet fragment around 60 meters across is believed to have been behind the Tunguska Event, a powerful explosion that took place over Russia in 1908. The blast has been estimated at equivalent to 10-15 million tons of TNT - enough to destroy a large city.

The White House is to develop a policy on the space object impact threat by October next year.

Ignored by western media: Indonesian asteroid exploded with energy of 'small atomic bomb'

Spaceweather.com

Thu, 29 Oct 2009 10:07 EDT

Picture this: A 10-meter wide asteroid hits Earth and explodes in the atmosphere with the energy of a small atomic bomb. Frightened by thunderous sounds and shaking walls, people rush out of their homes, thinking that an earthquake is in progress. All they see is a twisting trail of debris in the mid-day sky.

This really happened on Oct. 8th around 11 am local time in the coastal town of Bone, Indonesia. The Earth-shaking blast received remarkably little coverage in Western press, but meteor scientists have given it their full attention. "The explosion triggered infrasound sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) more than 10,000 km away," report researchers Elizabeth Silber and Peter Brown of the Univ. of Western Ontario in an Oct. 19th press release. Their analysis of the infrasound data revealed an explosion at coordinates 4.5S, 120E (close to Bone) with a yield of about 50 kton of TNT. That's two to three times more powerful than World War II-era atomic bombs.

The asteroid that caused the blast was not known before it hit and took astronomers completely by surprise. According to statistical studies of the near-Earth asteroid population, such objects are expected to collide with Earth on average every 2 to 12 years. "Follow-on observations from other instruments or ground recovery efforts would be very valuable in further refining this unique event," say Silber and Brown.

Comment: We suspect that about 30 or 40 years ago word came down from higher up not to report any more anomalous observations in the skies from the public, coincident with the UFO cover-up. About two years ago spaceweather.com also reported a huge fireball seen over Portugal, Spain and France. A Lexis-Nexis search of all English language news produced no mention of it in the mainstream media in the following days. This article appeared in El Mundo.

Just this week the internet was ablaze with reports about a fiery meteorite filmed in a field in Latvia. One of the newspapers carrying this story completely changed its reporting of the event within hours of breaking it, deciding that it was a hoax because the impact crater was just "too tidy." We suspect this event was a genuine meteor impact, but that damage control went into overdrive to cover it up.

Remember what Victor Clube wrote:

[I]t is perhaps not so widely appreciated that the witchhunts and political upheavals of the seventeenth century in England - which modern authorities sometimes look upon as archetypal in respect of the circumstances which generally give rise to revolution - were directly attributed by contemporaries to the unsettling effects of an (observed) celestial circulation: these contemporaries speak of celestial signs which were deliveries of "God's providence" and which were evidently mediated by "God's revolution".

After the Krakatao volcano erupted (in Indonesia no less) the entire island converted to Islam. One can only imagine what a similar comet or asteroid event would do to a country such as the US. What better way to condition them to be obedient slaves by frightening them with controlled, preemptive, color-coded "terrorism" and blowing up a few skyscrapers.

September 2009

2009-09-05T04:45:00.002Z

Meteor Seen Along New Zealand

The Marlborough Express

Mon, 31 Aug 2009 13:00 UTC

A fiery meteor blazed a trail through the skies on Friday morning, with sightings reported from Christchurch to Rotorua.

Zoe Battersby, out for an early walk along Jimmy Amers beach in Kaikoura at around 6.10am, said she couldn't help but notice it.

"It was very bright the size of a streetlight. It looked like it fell into the sea," she said.

Alan Gilmore, resident superintendent of the Canterbury University Mt John Observatory, said meteors entered the atmosphere over New Zealand "several times a year", but he doubted that the rock made it to the ground or water level. "This meteor is very typical, and often they burn up at about 70 kilometres up," he said.

"They are coming into a thicker atmosphere, travelling at 30km a second.

"The friction is strong and they slow up and start to break up.

"It's like throwing a stone at a concrete path."

Mr Gilmore said as meteors broke up, witnesses often saw a bright flash known as a "terminal fireball".

Meteors could be seen from as far as 1000km away and at a height of 100km.

"They are spectacular, often a bright white centre which is the actual rock ... a tiny, brilliant star with a teardrop-shaped glow that's brilliant emerald green caused by the oxygen and the radiation coming off the rock."

Mr Gilmore said a sonic boom often heralded the rare occasion of a meteor landing.

He expected Friday's meteor entered the atmosphere somewhere over the North Island because of the range of reported sightings.

"The impression of closeness is deceptive.

"Because they are bright, people think [the meteorite] landed a couple of paddocks away."

Ireland: Huge 'sky explosion' investigated

BBC News
Fri, 04 Sep 2009 22:19 UTC

An Irish astronomy group is calling for help in tracing the origin of a huge explosion in the skies over the country on Thursday evening.

Astronomy Ireland said it was currently investigating the explosion, which occurred at 2100 BST.

A spokesman said the most likely explanation was a space rock or satellite crashing into the atmosphere.

The group wants anyone who witnessed the event to contact its website at www.astronomy.ie

Astronomy Ireland chairman David Moore said: "So far, reports have been registered by residents in west Cork, Kerry, Cavan and as far north as Donegal, thus suggesting that this spectacular event may have been witnessed by people all over the country.

"In the past two decades there have been two major explosions in the skies over Ireland.

"When we investigated these, we were able to conclude that one was a Russian military satellite that exploded over the country, and the other was a rock from space which we predicted would have fallen on Carlow and this rock was indeed found, becoming the last meteorite fall of the millennium."

Mr Moore said the explosion should not be confused with a hugely-bright star which was positioned just below the full moon on Thursday night.

"This was actually the planet Jupiter and it can be characterised by being by far the brightest star in the entire night sky," he said.

Rain of meteorites makes the moon hum

Rachel Courtland
New Scientist
Tue, 08 Sep 2009 21:38 UTC

The man in the moon is humming a tune, but thankfully the noise won't drown out sensors on future missions peeking at the lunar interior.

A steady barrage of small meteorite impacts should cause the moon to "ring", but no seismometers sent to the moon to date have been sensitive enough to hear it. So Philippe Lognonné at the Institute of Earth Physics of Paris and colleagues decided to work out how loud the ring is.

The team estimated the meteorite population in the solar neighbourhood, and calculated the likely seismic signals that would be created by a range of meteorite sizes and velocities as they strike the moon.

Apollo calibration

To determine how the vibrations from these impacts would be seen by seismometers, the team used data taken by Apollo seismometers four decades ago. These measured the vibrations created by the landings of lunar modules and spent rocket stages.

Since the precise locations and timing of these landings were known, they could be used to gauge how long it would take vibrations caused by meteorite impacts to travel through the moon, and how much the signals might dim.

Their calculations revealed space rocks with masses ranging from a gram to a kilogram do indeed create a hum, but it is subtle. Earth's hum - created by pounding waves - is more than 1000 times louder.

"This shows that all planets may hum, those with and those without atmosphere," says Lognonné.

It's oh so quiet

The moon-hum's quietness means future lunar seismometers should be able to peek deep within the moon without the hum creating problematic background noise, says Lognonné.

Instead seismometers can focus on measuring waves created by moonquakes, tremors created by a variety of sources, including the tidal tug of the Earth. Because seismic waves are sensitive to the type, arrangement and density of rocks they pass through, studying the quakes can reveal more about the moon's interior.

The network of seismometers left by the Apollo missions has been shut down since 1977, so Lognonné hopes more sensitive instruments will be sent to the moon soon. These could reach deeper than the Apollo network to measure the size of the moon's core. "The area within 500 kilometres of the centre of the moon is complete unknown to seismology," Lognonné says.

"I think [the study] is a great idea," says Clive Neal of the University of Notre Dame in Indiana, who was not associated with the research. "Estimating the actual background noise is critical for designing the next generation of seismometers to go to the moon."

The first instrument may be a seismometer proposed for Japan's Selene-2 moon mission, which aims to send a lander to the surface, perhaps as early as 2015.

Journal of Geophysical Research (in press)

Was Vancouver light show a meteor or space junk?

Kimberley Shearon
The Province
Sun, 13 Sep 2009 15:01 UTC

It wasn't a bird and it wasn't a plane. Was it a meteor?

Around 8 p.m. Saturday night a great, big ball of yellowy-white light streaked from east to west across the darkening sky.

Astronomer David Dodge said that the fireball was probably a meteor - basically a rock falling from space.

"It probably wasn't a piece of space junk. The reason why I saw that is that it was going from east to west, and 99.9 per cent of space stuff sent up there is not going east to west."

He said meteors fall to earth every day.

Most burn up before they enter the earth's atmosphere.

Saturday's meteor was notable only because it happened over a populated area Some eye-witnesses, however, had their doubts.

Steve Salsman, was out on his deck when he saw the white ball of light hurtling through the dusky night air.

"It was at about the height of an airplane and had a long red tail," he said.

When the fiery ball appeared to break up, Salsman said he automatically thought that the it might be a dead satellite re-entering the earth's atmosphere.

Another eye-witness, Miles Wishlow, also said he thought the fireball was space junk falling from the sky.

He saw a "shard" break off from the fireball.

"It looked like something man-made that was just way off-course."

The fireball itself, Wishlow said, didn't resemble anything he's seen then past.

"The shape wasn't a perfect circle," he said.

"It was so big and so low compared to the shooting stars and other meteor showers. It was a lot closer than anything I've ever seen."

Dodge said Saturday's meteor might have landed somewhere along Vancouver Island's west coast or in the Pacific Ocean - if it landed at all.

Space-enthusiasts, he said, would be hard-pressed to find a chunk of the meteor, even if it did make it to earth.

"It was something 100 km over its ground path travelling at 70 km per second," he said.

"The human eye has a tough time dealing with that and tends to go for the easy answer. It's not in our neighbour's backyard."

Dodge also pointed out that once a meteor lands on earth it is no more remarkable than a regular old rock.

The biggest difference is that space rocks get to go out in a blaze of glory.

"It was quite breathtaking. Four of us were just standing there watching it," said Wishlow.

Sue Kendall was at her Saturna Island home on the phone with her son in Vancouver when she saw the bright, fast-moving light.

"I said, 'Oh my goodness,' and he looked up and saw it too," she said. "Your brain takes a moment to process it....it was amazing."

Jupiter Captured Comet as Temporary Moon

Nancy Atkinson
Universe Today
Sun, 13 Sep 2009 00:00 UTC

Jupiter's gravity well has been known to capture objects - evidenced by the recent impact on the gas giant discovered by amateur astronomer Anthony Wesley. But one object captured by Jupiter in the mid 1900's was later able to escape from the planet's clutches.

Researchers have found comet 147P/Kushida-Muramatsu was captured as a temporary moon of Jupiter, and remained trapped in an irregular orbit for about twelve years. "Our results demonstrate some of the routes taken by cometary bodies through interplanetary space that can allow them either to enter or to escape situations where they are in orbit around the planet Jupiter," said team member Dr. David Archer.

With this discovery, five such objects have now been discovered where the phenomenon of temporary satellite capture (TSC) has occurred, but this new research suggests it might happen more frequently than was expected. Kushida-Muramatsu orbited Jupiter between 1949 and 1961, the third longest capture period of the five objects.

An international team led by Dr. Katsuhito Ohtsuka modeled the trajectories of 18 "quasi-Hilda comets," objects with the potential to go through a temporary satellite capture by Jupiter that results in them either leaving or joining the "Hilda" group of objects in the asteroid belt. Most of the cases of temporary capture were flybys, where the comets did not complete a full orbit. However, the research team used recent observations tracking Kushida-Muramatsu over nine years to calculate hundreds of possible orbital paths for the comet over the previous century. In all scenarios, Kushida-Muramatsu completed two full revolutions of Jupiter.

"Asteroids and comets can sometimes be distorted or fragmented by tidal effects induced by the gravitational field of a capturing planet, or may even impact with the planet," said Archer, as did comet D/1993 F2 (Shoemaker-Levy 9), which was torn apart on passing close to Jupiter and whose fragments then collided with that planet in 1994. Previous computational studies have shown that Shoemaker-Levy 9 may well have been a quasi-Hilda comet before its capture by Jupiter. The object that impacted with Jupiter this July, causing a new dark spot may also have been a member of this class, even if it did not suffer tidal disruption like Shoemaker-Levy.

"Our work has become very topical again with the discovery this July of an expanding debris plume, created by the dust from the colliding object, which is the evident signature of an impact. The results of our study suggest that impacts on Jupiter and temporary satellite capture events may happen more frequently than we previously expected," said Asher.

The team has also confirmed a future moon of Jupiter. Comet 111P/Helin-Roman-Crockett, which has already orbited Jupiter three times between 1967 and 1985, is due to complete six laps of the giant planet between 2068 and 2086.

"Fortunately for us Jupiter, as the most massive planet with the greatest gravity, sucks objects towards it more readily than other planets and we expect to observe large impacts there more often than on Earth. Comet Kushida-Muramatsu has escaped from the giant planet and will avoid the fate of Shoemaker-Levy 9 for the foreseeable future," said Asher.

The discovery is to be presented at the European Planetary Science Congress in Potsdam.

Catastrophic Darkness

Jeremy Hsu
Astrobiology Magazine
Mon, 14 Sep 2009 04:24 UTC

© Donald E. Davis
This painting depicts an asteroid slamming into tropical, shallow seas of the Yucatan Peninsula in what is today southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 65 million years ago, is believed to have caused the extinction of the dinosaurs and many other species on Earth.

New studies of mixotrophic algae have shown how such organisms could survive the darkened skies that follow a major asteroid impact. Such studies indicate how life manages to survive after a mass extinction event.

A dinosaur-killing asteroid may have wiped out much of life on Earth 65 million years ago, but now scientists have discovered how smaller organisms might have survived in the darkness following such a catastrophic impact.

Survival may have depended upon jack-of-all-trades organisms called mixotrophs that can consume organic matter in the absence of sunlight. That would have proved crucial during the long months of dust and debris blotting out the sun, when plenty of dead or dying organic matter filled the Earth's oceans and lakes.

"Mixotrophs are very good at stabilizing situations by using whatever resources are there, and can often provide what resources there aren't," said Harriet Jones, a biologist at the University of East Anglia in the UK. "They're very good at coping in extreme environments, and enabling other organisms to live."

Jones and her colleagues tested the limits of mixotrophs by subjecting them to six months of low light or complete darkness. The mixotrophs not only thrived, but also surprised researchers by helping sunlight-dependent organisms also survive pitch black conditions.

Simulating catastrophe

Scientists have long debated the overall impact of the K-T extinction that may have heralded the end of the dinosaurs, but most researchers agree that such an event would have thrown up enough dust and debris to darken Earth's skies for about six months. A lack of sunlight would have killed off a majority of plants, eliminating the food supply for animals higher up the food chain.

Many scientists assumed that even smaller organisms would struggle just to stay alive during months of almost complete darkness. Some previous studies even looked at how some organisms such as mixotrophs can survive low light and low food conditions. But no one had tried to test how well mixotrophs would survive the catastrophic environment following something such as the K-T event, Jones said.

"The literature was always saying in that biological production would cease in a post-catastrophic environment," Jones noted. "We felt that because of what mixotrophy algae could do, that wasn't always the case."

Jones joined forces with Charles Cockell, a microbiologist at the Open University based in the UK who specializes in catastrophic environments, as well as other researchers. They tested both freshwater and ocean mixotrophs under conditions ranging from low light to complete darkness for six months, and added food sources during short-term experiments to simulate decaying organic matter.

However, Jones and her colleagues also wanted to see how mixotrophs fared when living together with phototrophs, or light-dependent organisms. They tested mixotrophs and phototrophs separately and together under the different light conditions.

Live together or die alone

Turns out that the mixotrophs survived all the experiments, and some even grew under the low light conditions. Their ability to consume other organisms or organic matter helped them rebound quickly after low light returned, perhaps similar to the clouds of dust and debris finally beginning to clear.

But the real shock came from how well light-dependent organisms did when living with the mixotrophs. No photosynthesis could take place under the complete darkness, but the phototrophs mostly managed to survive based on nutrients cycled by the active mixotrophs.

"We were extremely surprised at how well phototrophs did during six months darkness, when they can't eat at all," Jones said. Such findings may cause researchers to rethink how well certain life forms survived the catastrophic impacts that dot Earth's geological record.

Furthermore, the mixotroph activity allowed the phototroph populations to rebound quickly back to normal within a month. And in the end, both mixotrophs and phototrophs tended to fare better when living together.

"So long as mixotrophs are cycling nutrients, [phototroph] algae can take off quickly and get the life cycle going," Jones explained.

Life lessons for survival

Only one low light condition saw phototrophs fail to survive while living with mixotrophs. The phototrophs may have used too much energy trying to do photosynthesis in the weak light, or perhaps the hungry mixotrophs simply fed on their fellow organisms.

"You can only do so much in a flask, and obviously the mix of species would be much greater in a natural environment," Jones pointed out.

Still, the overall results suggest how mixotrophs provide a cushion against catastrophe for certain ecosystems, and may even prevent huge population crashes. The research is further detailed in the July/August issue of the journal Astrobiology.

Jones and her colleagues plan to conduct more studies with greater mixes of species, in an environment that would more closely resemble the natural world. They also want to shorten experiments to three months rather than six.

That looks all well and good for the smaller organisms. But humans, who would have a much harder time feeding themselves if the skies went dark, may want to plan on how to prevent such catastrophic asteroid impacts in the future.

Mini-Comets Within a Comet Lit Up 17P/Holmes During Megaoutburst

PhysOrg
Wed, 16 Sep 2009 13:41 UTC

Astronomers from the University of California, Los Angeles and the University of Hawaii have discovered multiple fragments ejected during the largest cometary outburst ever witnessed. Images and animations showing fragments rapidly flying away from the nucleus of comet 17P/Holmes will be presented by Rachel Stevenson at the European Planetary Science Congress in Potsdam, Germany, on Wednesday 16 September.

Stevenson, together with colleagues Jan Kleyna and David Jewitt, began observing comet Holmes in October 2007 soon after it was reported that the small (3.6 km wide) body had brightened by a million times in less than a day. They continued observing for several weeks after the outburst using the Canada- France- Hawaii Telescope in Hawaii and watched as the dust cloud ejected by the comet grew to be larger than the Sun.

The astronomers examined a sequence of images taken over nine nights in November 2007 using a digital filter that enhances sharp discontinuities within images. The filter, called a Laplacian filter, is particularly good at picking out faint small-scale features that would otherwise remain undetected against the bright background of the expanding comet. They found numerous small objects that moved radially away from the nucleus at speeds up to 125 metres per second (280 mph). These objects were too bright to simply be bare rocks, but instead were more like mini-comets creating their own dust clouds as the ice sublimated from their surfaces.

"Initially we thought this comet was unique simply because of the scale of the outburst," said Stevenson. "But we soon realized that the aftermath of the outburst showed unusual features, such as these fast-moving fragments, that have not been detected around other comets."

© Jewitt, Stevenson, Kleyna
Image of comet Holmes from the 3.6-meter Canada-France-Hawaii telescope on Mauna Kea showing the large expanding dust coma. On the left, a 'raw' image is shown, in which the brightness reflects the distribution of dust in the coma of the comet (the nucleus is in the bright, point-like region to the upper left of center). On the right is shown the same image after application of the Laplacian spatial filter, to emphasize fine structures. The white/black circular objects are background stars enhanced by the Laplacian filter.

While cometary outbursts are common, their causes are unknown. One possibility is that internal pressure built up as the comet moved closer to the Sun and sub-surface ices evaporated.

The pressure eventually became too great and part of the surface broke away, releasing a huge cloud of dust and gas, as well as larger fragments.

Surprisingly, the solid nucleus of comet Holmes survived the outburst and continued on its orbit, seemingly unperturbed. Holmes takes approximately 6 years to circle the Sun, and travels between the inner edge of the asteroid belt to beyond Jupiter. The comet is now moving away from the Sun but will return to its closest approach to the Sun in 2014, when astronomers will examine it for signs of further outbursts.

Rare Meteorite Found by 'Fireball' Observatory

Hazel Muir
New Scientist
Thu, 17 Sep 2009 23:36 UTC

© Desert Fireball Network, funding from STFC and the EU
This all-sky image was taken by the Desert Fireball Network in Western Australia with a fish-eye lens. The film is exposed for most of the night, so stars trace long curves; the white streak diagonally across them is a firebal

A rare meteorite that may have been born in Earth's neighbourhood has been found using a new 'fireball' observatory in Australia.

Scientists can learn how the solar system formed by studying meteorites that originated in different places within it. The trouble is, they don't know where the vast majority of meteorites actually came from.
"Trying to interpret what happened in the early solar system without knowing where meteorites are from is like trying to interpret the geology of Britain from random rocks dumped in your back yard," says Phil Bland at Imperial College London.

To remedy that, Bland's team set up the Desert Fireball Network in Western Australia's Nullarbor Desert in 2006. This trial network, currently with four robotic cameras spread over roughly 250,000 square kilometres, exposes photographic film to clear skies throughout the night.

If the cameras record a bright meteor, or fireball, as a rock falls through Earth's atmosphere, scientists can calculate its trajectory by triangulation, estimate the rock's likely landing site, then look for it.

Small parent

Following the network's first observation of a fireball on 20 July 2007, search parties found three fragments of the resulting meteorite, named Bunburra Rockhole, in 2008 and 2009.

The meteorite is made of basalt, the most common type of solidified lava on Earth. Scientists typically assume that basaltic meteorites are chips off the giant asteroid.

But Vesta is so large - roughly 530 kilometres across - that gravity caused its component materials to settle into different layers soon after its formation. The compounds in this meteorite, by contrast, are better mixed, suggesting it came from a smaller asteroid a few tens of kilometres wide.

Molten rock

Orbital calculations suggest this parent asteroid orbited in the innermost side of the asteroid belt between Mars and Jupiter until a collision chipped Bunburra Rockhole off the asteroid around 10 or 20 million years ago.

But though its parent body once orbited inside the asteroid belt, it may have been born closer to the sun. A theory proposed in 2006 argues that molten rock swirled around the young sun only in the current region of Venus, Earth and Mars, with many molten blobs subsequently flung out to the innermost asteroid belt.

In that case, Bunburra Rockhole could represent the type of material that clumped together to build Earth. "Our big question is - what were the building blocks for the terrestrial planets?" says Bland. "This rock gets us a little bit closer to that."

Journal reference: Science (DOI: 10.1126/science.1174787)

Astronomical Birth Event Results in a Multitude of 'Baby' Comets

Helen Altonn
Honolulu Star Bulletin
Thu, 17 Sep 2009 01:03 UTC

Astronomers who were dazzled by the 2007 explosion of a comet into the largest object in the solar system have discovered it gave birth to a bunch of baby comets.

Reporting the "largest comet birth ever seen" were David Jewitt, Rachel Stevenson and Jan Kleyna, who observed the event through a Mauna Kea telescope.

Jewitt, a professor, and Stevenson, his graduate student, left the University of Hawaii Institute for Astronomy this summer to join the University of California, Los Angeles. Kleyna is an astrobiology postdoctoral researcher at the institute.

They and others on an institute team observed the spectacular outburst of Comet 17P/Holmes in October and November 2007 from the Canada-France-Hawaii Telescope on Mauna Kea.

The normally obscure comet burst from a tiny nucleus of ice and rock into an object larger than the sun. The astronomers measured the mass of ejected dust at 900,000 miles across. The diameter of the sun, by comparison, is 865,000 miles.

"It was quite an event," Kleyna said in an interview yesterday. "We got some very high-quality data with a very large camera on the CFH Telescope."

He said the astronomers digitally enhanced the images and "over several nights found these bright spots" flying away from the nucleus of the comet at speeds of up to 280 mph.

"We concluded these probably were pieces of icy substance expelled from Comet Holmes like mini-comets," he said.

If they were solid chunks of ice they would have been invisible but they were bright with activity, creating their own dust clouds as surface ice vaporized and transformed into gas, Kleyna said.

"There have been some fragmented comets," Kleyna said, "but I don't think we've seen an eruption that generated many comets before."

"Initially, we thought this comet was unique simply because of the scale of the outburst," Stevenson said in a statement. "But we soon realized that the aftermath of the outburst showed unusual features, such as these fast-moving fragments that have not been detected around other comets."

The team continued observing for several weeks. Jewitt, in a Star-Bulletin interview in 2007, said the comet was expanding at about 1,100 mph and was "an unprecedented million times brighter" than before.

What the astronomers saw was "just awesome," Jewitt said, and "very, very weird. An outburst by a factor of a million is staggering, and I don't know of a previous case like this," he said as he and his team studied the expanding comet.

Sightings of the baby comets were reported at the European Planetary Science Congress this week in Potsdam, Germany.

Comet Holmes was discovered in an outburst in November 1892, then again in January 1893, probably when the comet was at its closest to the sun, Jewitt said in 2007.

It takes Comet Holmes about six years to circle the sun, traveling between the inner edge of the asteroid belt to beyond Jupiter. Its next closest approach to the sun will be in 2014.

Kleyna said the astronomers are still analyzing data from the 2007 observations. "There are other interesting details of the comet we're looking at."

What Do Dinosaurs And The Maya Have In Common?

Science Daily
Mon, 21 Sep 2009 07:01 EDT

One of the world's most famous asteroid craters, the Chicxulub crater, has been the subject of research for about twenty years. The asteroid impact that formed it probably put an end to the dinosaurs and helped mammals to flourish.

Together with an Anglo-American team, an ETH Zurich researcher has studied the most recent deposits that filled the crater. The results provide accurate dating of the limestones and a valuable basis for archaeologists to research the Maya.

The discovery of the Chicxulub asteroid crater was detective work: in 1980, based on iridium anomalies in clay sediments - which could only be formed extraterrestrially - the American physicist Walter Alvarez postulated a devastating asteroid impact at the transition from the Cretaceous to the Paleogene around 65 million years ago.

Another ten years passed before the associated crater was discovered on the Yucatan peninsula. Research work since then has focused mainly on the structure of the crater, which has been buried in a layer of sediment up to two kilometres thick since its formation and which can only be studied using boreholes or geophysical methods.

Little is known about the sediments close to the surface. Most of the geological maps also originate from the time before the Chicxulub crater was discovered, and do not completely reflect the geology.

Crater ring as a geological boundary

© Geological Survey of Canada
Chicxulub crater gravity map - white dots represent the locations of water-filled sinkholes

Together with American and English researchers, Adrian Gilli, Senior Lecturer at the Geological Institute of ETH Zurich, has now filled in a few of the gaps in the knowledge about the near-surface rock deposits. Gilli says, "The crater ring of the Chicxulub crater is scarcely recognisable in the terrain." This is despite the fact that it is distinctly different, geo-morphologically speaking, from the crater interior: the ring, which is about five kilometres wide and has a radius of approximately 90 kilometres around the port of Chicxulub, is criss-crossed by fractures that also occur frequently outside the crater ring.

The limestone along these faults has been riddled with holes and eroded by rain and groundwater. A process known as karstification has to date created about 3000 circular collapses forming small basins filled with groundwater. The Maya called these basins "d'zonot", or "cenotes", regarding them as a direct connection to the underworld and using such places as sacrificial sites.

Crater sediments distinctly younger

Previously, the rocks outside the crater ring were suspected to be older than those inside, but now researchers have for the first time been able to determine their precise age using a method based on the isotope ratios of strontium 87 to strontium 86 in the limestone, thus confirming their suspicions.

The rock samples inside the ring gave an age of between 2.3 and 6 million years. On the other hand, the rocks outside the ring showed more variable strontium isotope ratios and are from 10 to 33 million years old. Gilli suspects that the crater basin had been covered by seawater for a prolonged time, which allowed the more recent sediments to be deposited there.

The results help to understand the geology better and to re-draw and refine the outdated maps. Archaeology research can also benefit from the geologists' work: for example, the life of the Maya, whose important settlements Mayapán and Chichén Itzá are located in these two geologically different regions, can be better researched on the basis of the strontium data.

Gilli explains, "We really wanted to carry out a purely geo-archaeological study in which, initially, the crater played no part at all." The aim was to refine an earlier strontium isotopes study of the rocks around the former Maya sites by adding 72 new samples to enable the identification of small-scale variations in the isotope ratio. This is because the transitions between regions with a different ratio of strontium 87 to strontium 86 can be particularly important: Gilli says, enthusiastically, "We can obtain a very large amount of information about the lifestyle of the people from settlements at such boundaries, such as the Maya city of Mayapán."

Geology and archaeology complement each other

© Geological Survey of Canada
Shocked quartz grains produced by the impact (intracrater breccia sample Y6 N14 of the Chicxulub crater)

For instance, the fine-mesh geological measurement network in conjunction with the biological strontium isotope values makes migration movements visible. It could yield knowledge about where the Maya obtained their building materials or where they cultivated their maize.

This is because the weathering of rocks carries strontium into the soil and from there into plants. When eaten by humans or animals in food, strontium instead of calcium is incorporated into teeth when they are formed in childhood. If detailed strontium isotopes maps are available, this enables the region in which a person grew up to be determined. Gilli says, "It gets particularly exciting if the origin of the rulers of the various Maya towns can be determined. This in turn allows conclusions to be drawn about the social structures of the Maya."

The scientist is convinced that the geological analyses of the strontium isotope ratios form an important basis for the work of the archaeologists, who are working ever more frequently with the biological strontium isotopes from bones or teeth.

Chicxulub asteroid crater

The asteroid with a diameter of about ten kilometres that created the Chicxulub crater most probably caused the worldwide extinction of species at the boundary between the Cretaceous and the Palaeogene. The event caused the extinction of about 75 percent of all species.

Its effect was due mainly to the fact that it impacted into rocks rich in carbonate and anhydrite. This hurled massive amounts of carbon dioxide (CO2) and sulphur dioxide (SO2) into the atmosphere. It is estimated that between 200 and 3000 cubic kilometres of sediments vaporised, releasing 35 to 700 million tons of sulphur and 10 billion tons of CO2 into the atmosphere.

The ozone layer would probably have been destroyed within a very short time, and there must have been complete darkness over the Earth for months due to the dust in the atmosphere. This had serious short- and long-term consequences for the climate and biosphere. The crater that remains has a diameter of 180 kilometres and extends from the Yucatán peninsula to the Gulf of Mexico.

Maya

The first evidence of the Maya in Central America can be traced back to 3000 B.C. Over the course of history, their cultural centres moved from the uplands to the lowlands and finally to the north of the Yucatán. Chichén Itzá in the north-west of the Yucatán peninsula flourished during the classical period, whereas Mayapán was the last Maya capital in the north of the peninsula.

When the Spanish arrived in the late 15th century, the centres of post-classical Maya culture were in the extreme north of the Yucatán, while the central lowlands remained only thinly populated. Today, around 6.1 million Maya still live on the Yucatán peninsula and in Belize, Guatemala and Honduras.

Gilli A. et al.: Geological and archaeological implications of strontium isotope analysis of exposed bedrock in the Chicxulub crater basin, northwestern Yucatán, Mexico. Geology (2009), 37, 723-726, doi:10.1130/G30098A.1

Sept. 25, 2002: Mysterious Meteorite Dazzles Siberia

Randy Alfred
Wired
Fri, 25 Sep 2009 09:47 EDT

2002: A large fireball flashes across the night skies of the Irkutsk region of Siberia. What may have been a comet causes electrical circuits to come alive and leaves residents worrying about radioactivity.

Eyewitnesses saw the sky light up. More than a hundred people in the sparsely settled area reported seeing it.

At least one person fell to the floor in horror, believing that some religious doomsday had arrived. Others were sure that nuclear war had broken out.

The region was in an accustomed power blackout that night. But even as the meteor's visible energy lit up the skies outside, its strong electrical field activated the power grid. Residents reported that the lamps in their homes turned on for a few seconds.

People who were outside heard a buzzing, crackling sound in the air. The tops of fence posts lit up with electrical discharges.

The impact shattered windows for a dozen miles around and was felt up to 60 miles away. Scientists in Irkutsk recorded "seismic waves comparable to a middle-power earthquake."

Early reports indicated that local people may have suffered mild radiation poisoning, symptomized by aching joints, kidney problems and high blood pressure.

Hunters who first explored the area near the presumed impact reported an area of downed trees surrounded by charred forest.

The Institute of Solar and Earth Physics of the Siberian division of the Russian Academy of Sciences wanted to investigate, but was hampered by a lack of funds and the remoteness of the area. It was May 2003 before a scientific expedition could reach the hilly forests of Bodaibo, northeast of Irkutsk, and Lake Baikal.

Scientists found about 40 square miles of trees smashed in the pattern associated with big explosions. The meteorite had broken up before hitting the ground and left a score of craters, up to 65 feet in diameter. Nearby tree stumps were shattered or burned.

A U.S. spy satellite that had picked up the blazing ball at about 40 miles altitude lost it a little below 20 miles: It's possible that's where the ball exploded.

U.S. military analysts estimated the explosion as equivalent to 0.2 to 0.5 kilotons, though Russian physicist Andrey Olkhovatov placed it much higher at 4 to 5 kilotons.

No large fragments were found, only tiny hollow spheres, generally less than 0.1 to 0.2 millimeters diameter. The brown and dark-brown particles contained oxide and silicate minerals typical of meteorites, along with pyrite with nickel content, and various iron compounds. None of these is typical of the local geology.

Some sources say gamma radiation was at background level, but others say local water samples showed high levels of tritium, along with radioactive isotopes of cobalt and cesium.

Whether the fireball was rock that pulverized or, as some Soviet scientists concluded, an icy comet, there's this scary fact to consider: It was not picked up in advance by any existing warning systems. If the fireball had exploded on or over a major city, it could have killed tens of thousands of people.

Flashback: Siberia meteorite flattens 40 sq miles

Robin Shepherd
Times Online
Sat, 07 Jun 2003 14:30 EDT

If it had hit Central London, Britain would no longer have a capital city. The force of the meteorite that hit eastern Siberia last September destroyed 40 square miles of forest and caused earth tremors felt 60 miles away.

An expedition from Russia's Kosmopoisk institute has only recently reached the site in a remote area north of Lake Baikal because of bad weather and difficult terrain, the Interfax news agency said yesterday.

Fragments of the meteorite had apparently exploded into shrapnel 18 miles above the Earth with the force of at least 200 tonnes of TNT.

At the time, Russian media reported that villagers 60 miles away had witnessed a gigantic fireball screeching down from the sky, causing windows to rattle and house lights to swing as they were hit by blast waves on September 25. There were no reported casualties.

Flashback: 200 Tons of TNT Falls on Taiga

FarShores News
Sun, 03 Aug 2003 14:31 EDT

According to Yekaterina Shestakova, a town hall official, the expedition consists of five people, three scientists from the Moscow Meteorite Committee and two from Irkutsk. The expedition will go down the Vitim river from Bodaibo to the village of Vitimsky, from where it will proceed on foot to the place where the mysterious celestial body is presumed to have fallen.

It will be recalled that a large bolide entered the atmosphere over the villages of Vitimsky and Mama, in the Mama-Chuya district, on the night of September 24-25, 2002, at an angle of 32 degrees over the horizon and an altitude of 60 kilometers. Then there was a flash at 30 kilometers above the earth's surface which was registered by Americans. According to the U.S. military, the explosion occurred at 58o 13.6, s.l. and 113o 27.6, e.lat.

A team from Yekaterinburg is already working in the area: Twelve scientists and undergraduates are exploring the area where the U.S. satellite registered a second point of the bolides path at an altitude of 30 kilometers, canvassing eyewitnesses and finding numerous traces of the bolide.

By the end of July yet another team of Irkutsk scientists, led by Sergei Yazev, director of the Irkutsk University Astronomic Laboratory, will arrive at the Mama-Chuya district. "All four expeditions will be working independently," Sergei Yazev said.

"We want to study different sections of the bolides flight path." The scientists are especially interested in the virtually unexplored area - from the point where the bolide was registered by the U.S. satellite (30 kilometers over the earths surface) and the place where it presumably fell to the ground. Scientists believe that this area is 30 kilometers to 50 kilometers northeast of that point.

Samples of the snow taken in the area of the meteorites fall were found to contain remnants of meteorite substance - particles of iron, nickel, and chrome that are usually present in meteorites. Furthermore, particles of enstatite, nifeline, and cristobalite were discovered. The last mentioned element is a modification of ordinary quartz that has been subjected to high temperature impact. This rarely happens on earth. In addition, cristobalite and nifeline virtually never occur together. "It seems that a fairly large bolide exploded in the atmosphere," Sergei Yazev says. "It had a 200-ton TNT equivalent. There is nothing to suggest that the body that blew up was man-made - no trace of rocket fuel or increased radiation level or elements of metal structures. Apparently it was a stone or iron-and-stone bolide. Its dimensions have yet to be established."

According to eyewitness accounts, a huge star left a shining curve in the sky, falling somewhere in the cone-shaped hills. The dazzling flash lit up the taiga for a few seconds, as though bathing it in electric light, whereupon came an explosion, so powerful that windows were shattered in houses for dozens of kilometers around. Meteorites are usually given the name of the nearest populated area. It so happens that in 1902, a Bodaibo meteorite was found in the same area. The Sikhote-Alin meteorite fell in 1947. The Chulym bolide dropped on Siberia in February 1986.

The bolide flights were accompanied by a strong induction effect, with household electric bulbs and electronic equipment burning out. Presumably, similar phenomena occurred prior to the fall of the Tunguska meteorite. The moment the Vitim body fell, Georgy Kaurtsev, a Mama airport security officer, ran out into the street: "When the sound of the explosion came, a bulb went on although the switch was in the off position. I put on a jacket and rushed out. There is a meteorological station near the building. It is fenced off with wire mounted on 12 wooden poles. I saw balls of light, 20 to 30 centimeters in diameter, shining atop every one of them. Before long, they went out, but there was no trace left on the poles in the morning."

Maybe the scientists will find the place where the meteorite fell, and study it. Scientists believe it is critical to learn more about the nature of these "space aliens" in expectation of a more serious meteorite strike.

Source: Moscow News

Scientists See Water Ice In Fresh Meteorite Craters On Mars

ScienceDaily
Fri, 25 Sep 2009 01:08 EDT

© NASA/JPL-Caltech/University of Arizona
Earlier and later HiRISE images of a fresh meteorite crater 12 meters, or 40 feet, across located within Arcadia Planitia on Mars show how water ice excavated at the crater faded with time. The images, each 35 meters, or 115 feet across, were taken in November 2008 and January 2009.

NASA's Mars Reconnaissance Orbiter has revealed frozen water hiding just below the surface of mid-latitude Mars. The spacecraft's observations were obtained from orbit after meteorites excavated fresh craters on the Red Planet.

Scientists controlling instruments on the orbiter found bright ice exposed at five Martian sites with new craters that range in depth from approximately half a meter to 2.5 meters (1.5 feet to 8 feet). The craters did not exist in earlier images of the same sites. Some of the craters show a thin layer of bright ice atop darker underlying material. The bright patches darkened in the weeks following initial observations, as the freshly exposed ice vaporized into the thin Martian atmosphere. One of the new craters had a bright patch of material large enough for one of the orbiter's instruments to confirm it is water-ice.

The finds indicate water-ice occurs beneath Mars' surface halfway between the north pole and the equator, a lower latitude than expected in the Martian climate.

"This ice is a relic of a more humid climate from perhaps just several thousand years ago," said Shane Byrne of the University of Arizona, Tucson.

Byrne is a member of the team operating the orbiter's High Resolution Imaging Science Experiment, or HiRISE camera, which captured the unprecedented images. Byrne and 17 co-authors report the findings in the Sept. 25 edition of the journal Science.

"We now know we can use new impact sites as probes to look for ice in the shallow subsurface," said Megan Kennedy of Malin Space Science Systems in San Diego, a co-author of the paper and member of the team operating the orbiter's Context Camera.

During a typical week, the Context Camera returns more than 200 images of Mars that cover a total area greater than California. The camera team examines each image, sometimes finding dark spots that fresh, small craters make in terrain covered with dust. Checking earlier photos of the same areas can confirm a feature is new. The team has found more than 100 fresh impact sites, mostly closer to the equator than the ones that revealed ice.

An image from the camera on Aug. 10, 2008, showed apparent cratering that occurred after an image of the same ground was taken 67 days earlier. The opportunity to study such a fresh impact site prompted a look by the orbiter's higher resolution camera on Sept. 12, 2009, confirming a cluster of small craters.

"Something unusual jumped out," Byrne said. "We observed bright material at the bottoms of the craters with a very distinct color. It looked a lot like ice."

The bright material at that site did not cover enough area for a spectrometer instrument on the orbiter to determine its composition. However, a Sept. 18, 2008, image of a different mid-latitude site showed a crater that had not existed eight months earlier. This crater had a larger area of bright material.

"We were excited about it, so we did a quick-turnaround observation," said co-author Kim Seelos of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Everyone thought it was water-ice, but it was important to get the spectrum for confirmation."

Mars Reconnaissance Orbiter Project Scientist Rich Zurek, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., said, "This mission is designed to facilitate coordination and quick response by the science teams. That makes it possible to detect and understand rapidly changing features."

The ice exposed by fresh impacts suggests that NASA's Viking Lander 2, digging into mid-latitude Mars in 1976, might have struck ice if it had dug 10 centimeters (4 inches) deeper. The Viking 2 mission, which consisted of an orbiter and a lander, launched in September 1975 and became one of the first two space probes to land successfully on the Martian surface. The Viking 1 and 2 landers characterized the structure and composition of the atmosphere and surface. They also conducted on-the-spot biological tests for life on another planet.

Asteroid attack: Putting Earth's defences to the test

David Shiga
New Scientist
Thu, 24 Sep 2009 11:46 EDT

It looks inconsequential enough, the faint little spot moving leisurely across the sky. The mountain-top telescope that just detected it is taking it very seriously, though. It is an asteroid, one never seen before. Rapid-survey telescopes discover thousands of asteroids every year, but there's something very particular about this one. The telescope's software decides to wake several human astronomers with a text message they hoped they would never receive. The asteroid is on a collision course with Earth. It is the size of a skyscraper and it's big enough to raze a city to the ground. Oh, and it will be here in three days.

Far-fetched it might seem, but this scenario is all too plausible. Certainly it is realistic enough that the US air force recently brought together scientists, military officers and emergency-response officials for the first time to assess the nation's ability to cope, should it come to pass.

They were asked to imagine how their respective organisations would respond to a mythical asteroid called Innoculatus striking the Earth after just three days' warning. The asteroid consisted of two parts: a pile of rubble 270 metres across which was destined to splash down in the Atlantic Ocean off the west coast of Africa, and a 50-metre-wide rock heading, in true Hollywood style, directly for Washington DC.

The exercise, which took place in December 2008, exposed the chilling dangers asteroids pose. Not only is there no plan for what to do when an asteroid hits, but our early-warning systems - which could make the difference between life and death - are woefully inadequate. The meeting provided just the wake-up call organiser Peter Garreston had hoped to create. He has long been concerned about the threat of an impact. "As a taxpayer, I would appreciate my air force taking a look at something that would be certainly as bad as nuclear terrorism in a city, and potentially a civilisation-ending event," he says.

The latest space rock to put the frighteners on us was 2008 TC3. This car-sized object exploded in the atmosphere over Sudan in October last year. A telescope first spotted it just 20 hours before impact - at a distance of 500,000 kilometres - and astronomers say we were lucky to get any warning at all.

Thankfully, 2008 TC3 was far too small to do any damage on the ground, but we are nearly as blind to objects big enough to do serious harm. We have barely begun to track down the millions of skyscraper-sized asteroids zipping around Earth's neighbourhood, any one of which could unleash as much destructive power as a nuclear bomb on impact.

Asteroid impacts are not as rare as you might think. It is widely accepted that an asteroid or comet 30 to 50 metres across exploded over Tunguska in Siberia in 1908, flattening trees for dozens of kilometres all around. The chance of a similar impact is about 1 in 500 each year (Nature, vol 453, p 1178). Put another way, that's a 10 per cent chance of an impact in the next 50 years (see Should we panic?).

"Fifty-metre asteroids scare me to death," says Timothy Spahr, director of the Minor Planet Center in Cambridge, Massachusetts. "I could easily see a 50-metre object hitting in three days causing absolute pandemonium."

During the US air force planning exercise, the participating scientists explained that with so little warning there would be no hope of preventing an impact. Even Innoculatus's smaller 50-metre asteroid would weigh hundreds of thousands of tonnes, requiring an enormous push to change its trajectory appreciably - so much so that detonating a nuke near it in space would not provide a sufficient impulse so late in the game to cause a miss. To deflect an asteroid sufficiently, force would need to be applied years in advance (see Could we nuke it?).

In fact, it could make things worse by breaking the asteroid into pieces, some of which could be large enough to do damage, and even create a blizzard of meteors that would destroy satellites in Earth orbit.

Panic on the streets

Realistically, though, the nuclear option would not be on the table in the first place: the nuclear-tipped missiles sitting patiently in silos around the world are not designed to track and home in on an asteroid or even survive for more than a few minutes in space. Instead, we would simply have to brace ourselves for the impact.

The good news is that even a little warning makes a big difference, simply because it would allow us to predict the time and location of impact. In the case of 2008 TC3, just a few hours after the asteroid's discovery, NASA scientists completed calculations that predicted an atmospheric plunge over an unpopulated desert area of northern Sudan, with timing accurate to within a minute.

But participants in the planning exercise worried that if an asteroid posing an imminent threat to a populated area were discovered, and the situation were not handled properly, panic and lack of coordination could lead to chaos on the roads.

Spahr was not involved in the exercise, but shares those concerns. "With a three-day warning, you can walk away and be safe. But it scares me, given how poorly we've handled things of this nature in the past," he says, citing the failure to fully evacuate New Orleans ahead of hurricane Katrina in 2005. "I'm picturing people panicking and driving the wrong way on the freeway, screaming 'Oh my god, it's going to kill us!'"

To prevent panic and disorganised movement, it is crucial for authorities to develop an evacuation plan and communicate it to the public as soon as possible after discovery of the dangerous object, since such discoveries are posted automatically online and would cause a media firestorm.

Such measures should ensure the streets would be very quiet as an object such as Innoculatus plunges into the atmosphere and makes its final approach to Washington DC. The compression of the atmosphere in front of the asteroid and friction with the air would cause rapid heating. At lower altitudes, where the air is denser, the heating becomes so intense that the asteroid vaporises and explodes. For the Tunguska event, this happened at about 8 kilometres above ground.

Supersonic shock wave

If you were unfortunate enough to be looking up from directly below, the explosion would be brighter than the sun. The visible and infrared radiation would be strong enough to make anything flammable ignite, says Mark Boslough of Sandia National Laboratory in Livermore, California. "It's like being in a broiler oven," he says. Anyone directly exposed would quickly be very badly burned.

Even before the sound of the blast reaches you, your body would be smashed by a devastating supersonic shock wave as the explosion creates a bubble of high-pressure air that expands faster than the speed of sound. Planetary scientist Jay Melosh of Purdue University in New York once experienced a shock wave from an experiment that exploded 500 tonnes of TNT, a tiny blast in comparison with the blast from an asteroid. "I was standing on top of a hill about 1.5 kilometres away wearing earplugs," he recalls. Melosh says you would see the shockwave in the air due to the way it refracts light. "It's a shimmering bubble," he says. "It spreads out in complete silence until it reaches you, then you hear a double boom."

Melosh was at a safe distance, but at ground zero below an exploding asteroid, the shock wave would be powerful enough to knock down buildings. It would arrive about 30 seconds after the blazing hot flash of light, and could also knock any nearby planes out of the sky, Boslough says. Any surviving buildings would be pummelled by raging winds blowing faster than any hurricane can muster.

Of course, two-thirds of Earth's surface is ocean. While our atmosphere is likely to protect us from asteroids smaller than 100 metres across, anything larger hitting the ocean - including chunks of Innoculatus's rubble pile - would cause a giant splash that could smash coastal buildings with high-speed volleys of water. The tremendous damage and loss of life that would ensue if multiple cities around an ocean basin were flooded led NASA scientists in 2003 to rate ocean impacts by asteroids as far more dangerous than those on or over land.

Recent computer simulations offer some hope, though. They suggest that the monster waves generated by ocean impacts would typically break far from shore, dissipating most of their energy before they could reach cities - unless the impact was very close to the coast, of course. Another ray of hope is that 100-metre asteroids hit Earth only about one-tenth as often as 30-metre objects.

Lasting just one day, the 2008 US air force exercise could barely scratch the surface of the incoming-asteroid problem. Not surprisingly, it discovered that should the nightmare come true, there is no plan for how to coordinate the activities of NASA, emergency planners, the US military and other parts of government. Further planning exercises are needed: the time saved through early preparation will be crucial if an evacuation is ever required at short notice.

Our chance of having any prior warning at all for an approaching 30-metre asteroid is no better than 25 to 35 per cent with existing sky surveillance, calculates astronomer Alan Harris of the Space Science Institute in Boulder, Colorado. The sun washes out half of the sky with daylight, blinding us to 50 per cent of threatening objects. Even glare from the moon can hide unwelcome incoming guests.

What's more, two of the world's three leading asteroid surveys are based in Arizona, including the Catalina Sky Survey, which discovered 2008 TC3. The region tends to cloud over between July and September. "Shift 2008 TC3 back to July and forget it. It wouldn't have been seen," says Spahr.

Now picture this ugly scenario, which worried some participants in the air force exercise: an asteroid flies out of nowhere and explodes over a sensitive nuclear-armed region, like South-East Asia or the Middle East. There's a reasonable chance that such an airburst could be misinterpreted as a nuclear attack. Both produce a bright flash, a blast wave and raging winds.

Such concerns were one reason why, when NASA found 2008 TC3 in its sights, it not only issued a press release but also alerted the US State Department, military commanders, and White House officials, says Lindley Johnson at NASA headquarters, who oversees the agency's work on near-Earth objects. "If it had been going down in the middle of the Pacific somewhere, we probably would not have worried too much more about it, but since it was [going to be] on land and near the Middle East, we did our full alerting," he says.

There is one major way to improve our prospects - point more eyes at the skies. The European Space Agency wants to get into the monitoring game and may set its telescopes at the European Southern Observatory in Chile on the problem. This could fill a gap in the NASA-funded surveys, which are limited to watching the skies of the northern hemisphere, says Richard Crowther of the UK's Science and Technology Facilities Council, who is a consultant for ESA and heads a United Nations working group on near-Earth objects.

Be prepared

"Up to now, the US has taken the majority of the responsibility for dealing with this issue and I think it's time for other states to take on a more equitable share of that," he says.

Help will also come from two new US observatories designed to survey the entire sky visible from their locations every few days. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), will consist of four 1.8-metre telescopes, the first of which is already up and running in Hawaii. Plans are afoot to construct the 8.4-metre Large Synoptic Survey Telescope in Chile by 2015, though the project is still raising funds. These will improve the chances of an early detection and potentially extend warning times for 30-metre objects to more than a month. But even so, every ground-based lookout suffers from interference from the sun and moon.

A dedicated space telescope would fix this problem, but such a mission could cost more than a billion dollars. "We're talking about investing in an insurance policy," says Irwin Shapiro of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

Shapiro is leading a US National Research Council panel that by year's end will recommend a strategy to better address the threat from near-Earth objects. That study, along with the air force's report on its asteroid impact exercise, is intended to help the White House develop an official policy on the near-Earth object hazard by October 2010, which Congress has requested.

While asteroid impacts are much rarer than hurricanes and earthquakes, they have the potential to do much greater damage, Johnson warns: "It's not something I think there needs to be billions of dollars per year spent on, but it does warrant some priority in the list of things that we ought to be worried about." The cash would at least give us a better idea of when the next asteroid might strike. "From what we know today," he says, "it could be next week."

Comment: For a more in-depth study, read Meteorites, Asteroids, and Comets: Damages, Disasters, Injuries, Deaths, and Very Close Calls

Cosmic shock and awe: Fireball explodes over Argentina

Momento24
Tue, 29 Sep 2009 00:27 EDT

Yesterday afternoon the inhabitants of Mendoza, La Pampa, San Luis, and Cordoba saw a meteorite coming down the sky. It finally desintegrated with a loud explosion before it hit the earth.

The object, which initially scared the residents, was seen yesterday in the General Alvear Department. It could be a meteorite or space junk, but the place where it fell isn't known, according to what the Copernicus Institute said today.

From 18.30 there was a cloud in the sky and the explosion was felt almost by all people, asaid Julio Alcaraz, police officer of Santa Isabel, a town located 320 kilometers west of Santa Rosa and 40 miles south of the border with Mendoza.

The chief of the Copernicus Institute, Jaime Garcia, said that "by the color, it would apparently be a meteorite." He added that "the meteorite's location is unknown but according to the information collected it wouldn't have landed on Mendoza".

He defined meteorite as "any space object that wanders among the planets, the stars, and that enters the atmosphere.

"It was like a fireball," commented several neighbors to a local radio last night. Some Pampean residents said they photographed it and sent to it to the local media. In fact what is seen is a trail in the sky.

The object fell in the middle of the field in an area of 300,000 hectares which is uninhabited. The risks of fire outbrakes was immediately ruled out as it had been snowing all day long and it was very humid.

The Civil Defense chief of the commune, Roberto Trigues, confirmed that the raking "was held from 20 up to 23hs. They could establish the hypothetical triangulation with the apex at Punta del Agua, Agua Escondida and Chocico or Santa Isabel, a little more to the South, which would be the impact zone.

This explosion is produced before hitting the earth and logically, as it is an important explosion, it produces a blast of air which causes the shaking of glasses in the houses.

Finally, Trigues said that this is a very large area, so "I would say it might be hard to find something".

Jaime Garcia, amateur astronomer in charge of the Copernicus Institute in San Rafael, said "nothing can be confirmed until an object is found, but we can say that according to testimonies, it is very likely to be a metal object such as a meteor."

UK: Strange Fireball Seen in Night Sky

Malvern Gazette
Wed, 30 Sep 2009 16:19 EDT

A Bosbury man who witnessed a strange light in the sky on Saturday night is wondering if anyone else saw the same thing.

Mark Beard saw the orange glow at around 9.45pm to 10pm as he was standing outside his rural home.

He said: "I was at my back door looking east, and to my left, appearing above the tops of houses was a large fireball, a tenth the size of the moon."

He said it was orange and moved through the sky for about two or three minutes in a north-south direction. It then slowly started to fade and then disappear, fading out before it had reached the horizon in the south.

He said he had found news reports on the Internet of similar object being seen in Essex at about the same time on the same night.

"I've seen shooting stars and it didn't have the trail you see with them, but it was very, very bright," he said.