Celestial impacts can bring life as well as wipe it out, say the authors of a new study out of the University of Colorado at Boulder.
A case in point: the bombardment of Earth nearly 4 billion years ago by asteroids as large as Kansas would not have had the firepower to extinguish potential early life on the planet and may even have given it a boost.
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The Solar System often throws up surprises for astronomers, but the recent discovery of a 2- to 3-km wide asteroid called 2009 HC82 has sent observers in a spin. A retrograde spin to be precise.
This particular near-Earth asteroid (NEO) should have already been spotted as it has such a strange orbit. It is highly inclined, making it orbit the Sun backwards (when compared with the rest of the Solar System's planetary bodies) every 3.39 years. What's more, it ventures uncomfortably close (3.5 million km) to the Earth, making this NEO a potentially deadly lump of rock…
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The black arrows indicate the orientation of chevrons along the southern coast of Madagascar, but the white arrows indicate what computer models say should have been the orientation if they were caused by the impact of a space body in the Indian Ocean. Credit: Robert Weiss
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In 1979, the huge Chicxulub crater, measuring about 180 km (112 miles) in diameter, was discovered on the northern Yucatan Peninsula, Mexico. Scientists made the obvious conclusion that something rather large had hit the Earth in this location, probably causing all kinds of global devastation 65 million years ago. At around the same time, 65% of all life on the face of the planet was snuffed out of existence. The dinosaurs that roamed the planet up to that point were no more.
The timing of asteroid impact and the time of the mass extinction was too much of a coincidence to be ignored. When particles from the asteroid impact were discovered just below the Cretaceous-Tertiary (K-T) boundary, there was a strong causal link: the effects of the asteroid impact had driven the dinosaurs to extinction.
However, a problem with this theory has come to light. It turns out the Chicxulub impact may pre-date the K-T boundary by 300,000 years…
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If Earthlings discovered a large asteroid heading towards our planet, how would we react? But more importantly would the space agencies and/or world governments be prepared for such an event? "Mankind is now technically able to predict, sometimes several decades in advance, the trajectory of Near Earth Objects (NEOs)," said Frans von der Dunk, professor of space law at the University of Nebraska-Lincoln. "Additionally, existing space technology could deflect the vast majority of threatening asteroids." But even if a threatening object is discovered, von der Dunk said no mechanism exists for effective international decision-making on how to deal with a threat. To examine these issues, UNL hosted a conference on April 23 & 24, "Near-Earth Objects: Risks, Responses and Opportunities,” to look at the legal and institutional challenges of creating an international protocol of dealing with NEOs.
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If you stay out in the Sun too long, you'll eventually get a suntan (or sunburn); your skin will also get damaged and it will show signs of ageing faster. This might sound like a sunblock ad, but the same principal holds true for the small chunks of rock floating around in the Solar System. Yes, a young asteroid's surface will age prematurely, but it's not caused by the Sun's ultraviolet rays, it's caused by the solar wind…
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It may not look like much, but that drawing could save a life someday — or 7 billion.
David French, a doctoral candidate in aerospace engineering at North Carolina State University is proposing a new tool for the anti-asteroid arsenal.
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Officials are now saying the bright fireball seen over Virginia in the US on Sunday was probably a natural meteor event and not part of a Russian rocket, a reversal from yesterday's initial analysis. Space.com reported that an official from the U.S. Naval Observatory believed the loud boom and flash of light seen in the skies over Norfolk and Virginia Beach was likely the second stage of the Soyuz rocket that launched Expedition 19 to the International Space Station last Thursday. However, U.S. Strategic Command has since reported that the rocket re-entered Earth's atmosphere near Taiwan, on the other side of the world, several hours after the reports of the fireball. So both its timing and entry location rule out the rocket as the explanation for the fireball. But the investigation is continuing to determine exactly what the object was.
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Residents of Virginia in the US reported hearing booms and seeing flashes of light Sunday night, and originally, it was reported to be another possible meteor. But now officials from the U.S. Naval Observatory say it was likely the second stage of the Russian Soyuz rocket falling back to Earth. Parts of the rocket from last Thursday's launch to the International Space Station would have fallen to Earth about that same time. "I'm pretty convinced that what these folks saw was the second stage of the Soyuz rocket that launched the crew up to the space station," Space.com quoted Jeff Chester of the Naval Observatory in Washington, D.C.
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Remember in October 2008 when Asteroid 2008 TC3 hit the scene – literally? This was the first asteroid that was predicted –and predicted correctly — to impact the Earth. Luckily, it wasn't big enough to cause any problems, and its path was over a remote area in Africa. It streaked into the skies over northern Sudan in the early morning of October 7, 2008, and then exploded at a high 37 km above the Nubian Desert, before the atmosphere could slow it down. It was believed that the asteroid likely had completely disintegrated into dust. But meteor astronomer Peter Jenniskens thought there might be a chance to recover some of the remains of this truck-sized asteroid. And he was right.
Never before have meteorites been collected from such a high altitude explosion. Additionally, as it turns out, the assembled remnants are unlike anything in our meteorite collections, and may be an important clue in unraveling the early history of the solar system.
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Dusty debris around an old white dwarf star (NASA)
What will happen to all the inner planets, dwarf planets, gas giants and asteroids in the Solar System when the Sun turns into a white dwarf? This question is currently being pondered by a NASA researcher who is building a model of how our Solar System might evolve as our Sun loses mass, violently turning into an electron-degenerate star. It turns out that Dr. John Debes work has some very interesting implications. As we use more precise techniques to observe existing white dwarf stars with the dusty remains of the rocky bodies that used to orbit them, the results of Debes' model could be used as a comparison to see if any existing white dwarf stars resemble how our Sun might look in 4-5 billion years time…
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Another asteroid is set to make a close approach of 79,000 km according to NASA, a distance twice that of geosynchronous orbit around the Earth. Although the 15-20 metre-wide rock is not expected to cause any problems to Earth or satellites, some observers may be lucky to spot the faint light from 2009 FH as it passes.
Interestingly, this new object comes only two weeks after a larger (50 metre wide) asteroid was spotted passing the Earth at a similar distance. So it begs the question, why are we seeing so many asteroids lately?
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Recently, the Dawn spacecraft – on its circuitous route to the asteroid belt — used the gravity of Mars to provide a little 'kick' to the spacecraft's velocity. Universe Today finally had the chance to catch up with the team from the Dawn mission following this maneuver to find out how things went, and how the spacecraft is doing following the gravity assist operations. "The gravity assist accomplished exactly what we needed to get on course for Vesta," Dawn Chief Engineer Marc Rayman told UT. "In addition to the gravity assist, we decided to undertake some bonus instrument calibrations, taking advantage of flying by such a well-studied planet. In doing so, we obtained some performance data on some of our instruments." The image seen here of Mars' surface is one of the results of those calibrations.
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As I'm writing this (13:40 UT) a newly-discovered asteroid, 2009 DD45, is flying past Earth at only 74,800 km (46,478.5 miles or 0.000482 AU) away. That's only about twice the height of a typical geostationary communications satellite, and well inside the moon's orbit. According to Spaceweather.com, the 30- to 40-meter wide space rock is similar in size to the Tunguska impactor of 1908, but this time there is no danger of a collision. At closest approach on March 2nd, (which just occurred) 2009 DD45 will speed through the constellation Virgo shining as brightly as an 11th magnitude star. So if you're in the Pacific region like Hawaii or Tahiti, go out and take a look! But this rock is moving fairly fast, and by tonight, it will only be 13th magnitude, and fading fast.
UPDATE: Below see video of 2009 DD45 as seen from Australia:
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When Mars and Jupiter migrated to their present orbits around 4 billion years ago, they left scars in the asteroid belt that are still visible today.
The evidence is unveiled in a new paper in this week's issue of the journal Nature, by planetary scientists David Minton and Renu Malhotra from the University of Arizona in Tucson.
The asteroid belt has long been known to harbor gaps, called Kirkwood gaps, in distinct locations. Some of these gaps correspond to unstable zones, where the modern-day gravitational influence of Jupiter and Saturn eject asteroids. But for the first time, Minton and Malhotra have noticed that some clearings don't fit the bill.
"What we found was that many regions are depleted in asteroids relative to other regions, not just in the previously known Kirkwood gaps that are explained by the current planetary orbits," Minton wrote in an email. In an editorial accompanying the paper, author Kevin Walsh added, "Qualitatively, it looks as if a snow plough were driven through the main asteroid belt, kicking out asteroids along the way and slowing to a stop at the inner edge of the belt."
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