asteroids 2
it's an interesting thought experiment to consider what to do if we do discover an asteroid's going to obliterate the planet. first we confirm it. then we do something about it. if we have lots of time we can somehow give the thing a small nudge so it passes by harmlessly. however if we discover it late we drop everything and take drastic measures. like build the biggest goddam nuke ever. and put it on the biggest rocket ever made. and try to turn the giant monster into harmless pieces. there've been some pretty decent science fiction stories on the subject. and some pretty bad ones too.