sgsguru | Meteorites and Dead Dinosaurs (Reply)

Greg Bear talks about meteorites.

I get a kick out of the fact that the definitive article on very large oceanic meteorite impacts was published in "Analog Science Fiction". (The picture with the CNN article above is the cover of that issue of Analog.)

Also, it seems that all the attention goes to "asteroids". Asteroids are hunks of rock orbiting the sun, in the ecliptic, just like planets. As such, their orbits can be predicted for decades or centuries in advance. If we sight one that's going to hit us, we have a lot of time to figure out what to do about it.

If you want something to *really* worry about, think about long-period comets. They come in from a long way out, moving effectively at solar escape velocity, and can come in at any angle, not just in the ecliptic. If one of these came in on a collision course, how much warning would we have? I've poked at it a bit; my calculus is no longer up to it. My guess is no more than a couple of years, depending on how far out it was sighted. That isn't enough time to set up committees to talk about it ...