Asteroid Apocalypse

A few years ago, nobody worried about asteroids. Sure, maybe a big one wiped out the dinosaurs, but that was millions of years ago and Armageddon and Deep Impact are just sci-fi disaster movies, right? Perhaps not. NASA is now taking the threat from "Near Earth Objects" much more seriously these days, compiling data about potentially hazardous asteroids, or PHAs. Several observatories actually specialize in trying to track such objects. NASA's current count of space rocks capable of ending life as we know it is about 5,000.