Let's say an asteroid was coming for your city. How screwed are you?This video from PBS Space Time gives a lowdown on what would happen, and what we could do, if we're ever approached by an asteroid that could level cities. It turns out that our options are far less limited than you might think, as long as the asteroid is small enough. The more time you have to plan also makes a huge difference.If we knew ten years in advance, we do a number of things to divert its course in such a way that it would miss the Earth's orbit. We could detonate a nuke on the asteroid's side. We could smash a spaceship into it. We could, interestingly enough, paint one side of the asteroid bright enough so that the radiation pressure from the sun will actually divert the meteor. That's the same sort of pressure that drives solar sails.Our options here are getting kind of ridiculous, but they'll only be available if we even have programs in place to look for these city-killing asteroids in the first place.