Tag: asteroids

Geologists, using computer models, have reconstructed the size and impact velocity of a giant asteroid that hit the Earth approximately 3.26 billion years ago.

11:51 am

Geologists, using computer models, have reconstructed the size and impact velocity of a giant asteroid that hit the Earth approximately 3.26 billion years ago.

This is a fascinating result, but it is very important to recognize its very large uncertainties. The article for example says almost nothing about how these conclusions were reached, except for this one paragraph:

Lowe, who discovered telltale rock formations in the Barberton greenstone a decade ago, thought their structure smacked of an asteroid impact. The new research models for the first time how big the asteroid was and the effect it had on the planet, including the possible initiation of a more modern plate tectonic system that is seen in the region, according to Lowe. [emphasis mine]

I have highlighted that one word because it reveals a great deal. What they did was to create a computer model of the data they had, which was merely very unusual geology spread over a certain region called the Barberton Greenstone Belt. Note also that this region is not where the impact occurred. “The study’s co-authors think the asteroid hit the Earth thousands of kilometers away from the Barberton Greenstone Belt, although they can’t pinpoint the exact location.”

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A skydiver’s helmet cam captures a meteorite zipping past him as it falls.

2:11 pm

A skydiver’s helmet cam videotapes a meteorite zipping past him as it falls.

The incident happened back in the summer of 2012, when skydiver Anders Helstrup and other members of the Oslo Parachute Club took to the skies above Hedmark, Norway. Helstrup documented the jump with two cameras fixed to the front and back of his helmet. Helstrup tells NRK (the largest media outlet in Norway) that on the way down he felt “something” happen, but didn’t know what. It was only after landing and reviewing his camera footage that he discovered something shocking: a rock had fallen from the heavens and missed him by just a few yards.

Video below the fold. The news woman is annoying, but the footage is quite cool.
» Read more

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Astronomers have found an asteroid with its own rings.

10:07 pm

Astronomers have found an asteroid with its own rings.

Chariklo is the largest member of a class known as the Centaurs and it orbits between Saturn and Uranus in the outer Solar System. Predictions had shown that it would pass in front of the star UCAC4 248-108672 on 3 June 2013, as seen from South America. Astronomers using telescopes at seven different locations, including the 1.54-metre Danish and TRAPPIST telescopes at ESO’s La Silla Observatory in Chile, were able to watch the star apparently vanish for a few seconds as its light was blocked by Chariklo — an occultation.

But they found much more than they were expecting. A few seconds before, and again a few seconds after the main occultation there were two further very short dips in the star’s apparent brightness. Something around Chariklo was blocking the light! By comparing what was seen from different sites the team could reconstruct not only the shape and size of the object itself but also the shape, width, orientation and other properties of the newly discovered rings.

The team found that the ring system consists of two sharply confined rings only seven and three kilometres wide, separated by a clear gap of nine kilometres — around a small 250-kilometre diameter object orbiting beyond Saturn.

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An asteroid will eclipse the bright naked eye star Regulus for 14 seconds on March 19-20, and everyone in the New York City metropolitan area will be able to watch.

10:58 am

An asteroid will eclipse the bright naked eye star Regulus for 14 seconds on March 19-20, and everyone in the New York City metropolitan area will be able to watch.

Late on the night of March 19–20, the faint asteroid Erigone (eh-RIG-uh-nee) will briefly eclipse the bright naked-eye star Regulus for more than 20 million people in the New York metropolitan area and parts of Long Island, New Jersey, Connecticut, upstate New York, and Ontario. The star will vanish from sight for up to 14 seconds around 2:06 a.m. EDT on the morning of the 20th for New Yorkers, and a minute or two later farther north.

If the sky is clear, Regulus will be a cinch for anyone to spot — no astronomy experience required! Around 2 a.m. or a bit before, go out and face the Moon. Extend your arms straight out to your sides. Regulus will be straight above your right hand, roughly as high as the Moon is. It’s the brightest star in that area.

Scientists are also asking ordinary citizens to help gather data, which if sufficient will allow them to recreate a reasonably accurate silhouette of the asteroid, thus determining its size and shape.

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Another rock will fly past the Earth today, killing no one.

4:07 pm

Chicken Little report: Another rock will fly past the Earth today, killing no one.

The 33-foot-wide (10 meters) near-Earth asteroid 2014 EC will come within 34,550 miles (55,600 kilometers) of Earth’s surface this evening (March 6) — just 14 percent of the distance between our planet and the moon, which is about 239,000 miles (385,000 km) on average.

The key quote, however, is this:

Such back-to-back flybys are pretty special, though they can’t exactly be called rare events, [JPL scientist Don] Yeomans said. “For small asteroids, one would expect a flyby of the Earth, to within the moon’s distance, about every two weeks,” he said.

In other words, these flybys happen a lot, with no consequences.

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Hubble photographs the break-up of an asteroid.

8:36 am

Hubble photographs the break-up of an asteroid.

The ongoing discovery of more fragments makes it unlikely that the asteroid is disintegrating due to a collision with another asteroid, which would be instantaneous and violent in comparison to what has been observed. Some of the debris from such a high-velocity smash-up would also be expected to travel much faster than has been observed.

It is also unlikely that the asteroid is breaking apart due to the pressure of interior ices warming and vaporising. The object is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 480-million-kilometre distance from the Sun for much of the age of the Solar System.

This leaves a scenario in which the asteroid is disintegrating due to a subtle effect of sunlight that causes the rotation rate to slowly increase over time. Eventually, its component pieces gently pull apart due to centrifugal force. The possibility of disruption by this phenomenon — known as the YORP effect — has been discussed by scientists for several years but, so far, never reliably observed.

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A 100-foot diameter newly discovered asteroid will zip past the Earth inside the Moon’s orbit today at 4:07 pm Eastern.

9:35 am

Chicken Little report: A 100-foot diameter newly discovered asteroid will zip past the Earth inside the Moon’s orbit today at 4:07 pm Eastern.

The asteroid, dubbed 2014 DX 110, is about 100 feet in diameter and is set to come within 216,000 miles of Earth — a close shave by astronomical standards, considering our Moon orbits the Earth at a distance of about 238,900 miles.

While an object that size may not seem imposing, if it were to strike the Earth, it would release a devastating amount of energy greater than a nuclear weapon. The infamous asteroid that exploded over Tunguska, Siberia, on June 30, 1908, has been estimated to be about 30 meters to 60 meters — 100 feet to 200 feet — in diameter.

While it is true that the impact would be significant, this news report does the typical fear-mongering to make the story seem interesting. The problem, however, is that the detection of these fly-bys is becoming more frequent. The number of asteroids isn’t changing, but our ability to spot them is, and with more frequent discoveries comes more frequent news stories like this. I fear that such stories — fueled by press releases from various astronomy organizations — are going to begin to sound like a kid “crying wolf” to the general public. The threat from an asteroid impact is real, even if most asteroids miss us. Desensitizing the public to the threat is not a good thing.

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A September asteroid impact on the Moon captured by Spanish astronomers.

8:56 am

A September asteroid impact on the Moon captured as it happened by Spanish astronomers.

On 11 September 2013, Prof Jose M. Madiedo was operating two telescopes in the south of Spain that were searching for these impact events. At 2007 GMT he witnessed an unusually long and bright flash in Mare Nubium, an ancient lava-filled basin with a darker appearance than its surroundings. The flash was the result of a rock crashing into the lunar surface and was briefly almost as bright as the familiar Pole Star, meaning that anyone on Earth who was lucky enough to be looking at the Moon at that moment would have been able to see it. In the video recording made by Prof Madiedo, an afterglow remained visible for a further eight seconds. The September event is the longest and brightest confirmed impact flash ever observed on the Moon.

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Three relatively large near Earth asteroids have just been discovered.

10:13 pm

Chicken Little report: In October of last year three relatively large near Earth asteroids were discovered unexpectedly.

Read the report, which is the second notice at the link. I missed it at the time. Each of these new discoveries was interesting and surprising. Key quote: “The delayed discovery of 2013 US10 is a bit harder to explain, since current population models suggest that almost all near-Earth asteroids of this size and orbit should have already been found.” Apparently not.

In related news, a several hundred foot wide asteroid zipped past the Earth this evening.

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Mars Reconnaissance Orbiter spots a new crater on Mars.

12:38 pm

Mars Reconnaissance Orbiter spots a new crater on Mars.

The scar appeared at some time between imaging of this location by the orbiter’s Context Camera in July 2010 and again in May 2012. Based on apparent changes between those before-and-after images at lower resolution, researchers used HiRISE to acquire this new image on Nov. 19, 2013. The impact that excavated this crater threw some material as far as 9.3 miles (15 kilometers).

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An analysis of the rotation of the peanut-shaped asteroid 25143 Itokawa suggests that its smaller end is actually far denser than its bigger end.

9:03 am

An analysis of the rotation of the peanut-shaped asteroid 25143 Itokawa suggests that its smaller end is actually far denser than its bigger end.

Previously, some researchers have proposed that Itokawa is actually two asteroids in contact with one another, a scenario strongly supported by the new results, the team contends. It’s not clear whether the odd configuration results from the merger of a two-asteroid system or merely clumps of material that fell back together after a larger asteroid was blasted apart by an immense collision.

The researchers also found that the asteroid’s rotation is actually increasing by 45 milliseconds per year.

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