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Another Asteroid Close Call
james was one of a number of people that submitted the news that
the earth has had another near miss, this time with an asteroid. This particular one is thought to be about 300 meters in length, meaning that if it had struck the earth, it would have destroyed an area of say...South Africa. Not to mention the fall out. But
we don't need
a
better system
for watching the stars. Nope. Obviously not.
Here's a list of PHAs (Potentially Hazardous Asteroids) and a simulation of the orbit of this particular asteriod.
Tired of being "punished" by the Slashdot $rtbl since 2002. I'm now over at http://soylentnews.org/ .
isaac asimov wrote a neat book called a choice of catastrophes he addresses being hit by an asteroid while it is statistically possible it is highly unlikely.
Remember, Asimov was writing (in 1980) before Gene Shoemaker's work from the 60s and after became fully accepted. It really wasn't until all the work identifying impact craters on the earth that was inspired at least in part by Shoemaker's work, and by the Alvarez hypothesis on the K-T extinction (i.e., the asteroid that killed the dinosaurs), got underway that astronomers and geologists took the idea of large impacts seriously (most scientists thought that Meteor Crater was an extinct caldera before Shoemaker, despite the name). Also, Sagan et al.'s work on sandstorms in the Martian atmosphere in the 1970s, which helped to provide a possible mechanism for global effects from local impacts, wouldn't have been completely digested by the time Asimov was writing. Though Asimov was right that overpopulation is the most serious of the issues he deals with in the book (and of course few countries outside Asia take the problem seriously), it would be foolish to dismiss the threat of an impact.
You need to define "large" and "barely missing", to even understand what those assumptions are saying.
First, we're doing pretty well at tracking the really large earth-grazing asteroids now - for rocks at least a kilometer in diameter (picture the "little guy" that hit at the end of Deep Impact) we're tracking an estimated ~90% instead of 10% of them now, and the big improvement has come in the last five years or so.
For the stuff smaller than a kilometer (which don't threaten civilization, but can still be large enough to make much of New York City a memory), I don't know that we're doing much tracking at all. So what's your definition of "large"? Thanks to the heavy ocean cover and relatively sparse city covering of the land, odds are we'll get hit in a nice relatively non-fatal location before a city-buster earns its name. And we'll get hundreds or thousands of near misses before then. What's your definition of "barely missing"? I've heard it to refer to anything passing inside the moon's orbit, which is a target with 3,600 times the cross section of Earth. That's a near miss on a cosmic scale, not on a human one.
It's hard to set odds on something like this, but the most informed I've seen would give us about even odds of having a populated area smashed up (damage as much as a trillion dollars) sometime in the next millenium. Not such bad odds that we want to start putting up an "asteroid defense shield", but bad enough that some other valuable activities (pointing more telescopes at the sky, cataloguing asteroids, improving launch vehicle technology) become more valuable for this secondary reason.