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| Tue Jul 1 23:00:35 2008 Near Miss |
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| Tue Jul 1 23:00:35 2008 Near Miss The one that almost got us... |
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| I was just reading through the 26 June edition of
Nature. There are usually a few interesting tidbits in every issue. This issue
focused on "Cosmic Cataclysms": particularly impacts.
There was a good story on the Tunguska blast of 1908. I had recently read that Lake Cheko could be the remnants of the impact crater. Soundings had indicated a curious impact-shaped dimple at the bottom of the lake, and a follow-on visit was planned to look for meteorite debris at the bottom. However, the Nature article didn't think highly of the Lake Cheko theory. Another article, "The Burger Bar that Saved the World," was excellent. It talked to a group of long-time asteroid hunters that had started searching for near-Earth asteroids in the 70's, and they had a 30+ year perspective on how asteroid hunting had changed. Certainly the technology has changed a lot! And the idea that impacts were common on Earth was new. Many of the scientists claim that it was Alvarez's theory about the impact that killed the dinosaurs that really woke people up: here was proof that a rather small impact had decimated life on Earth. The article was a good read. It interspersed comments from several scientists to give an overview of how the field had evovled. But I was shocked by comments by Clark Chapman about a near-miss in 2004. He writes: In 2004, an object was discovered ... and the nominal calculated orbit had the asteroid hitting the Earth the next day. ... [JPL] concluded that there was something on the order of a 30% chance that this object would hit the Earth during the next three days. He noted that the European and North American observatories were desperately trying to observe the object to get better data, but weather was bad over both continents, and no one could see it. So we were debating late into the night, at what point should we go public with this? Wow. As it turns out, later observations revealed that the object was larger than originally thought, but also farther away. And so the collision chances dropped to around zero. But regardless, there was a period of a day or so when the world's leading experts thought there was a 30% probability that an asteroid would hit the Earth. Rusty Schweickart has since started the B612 Foundation (named after the asteroid in Saint Exupery's The Little Prince) which is attempting to establish protocols for engaging the United Nations and other bodies when an impact is deemed imminent. So sleep soundly, but not too soundly. Comments |
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