How They Will Get Us:
But it's probably OK: We've only found like 16 of these things zipping about. When you take into account the fact that our solar system is but a speck of fecal matter in the giant toilet that is the universe, the chances of one of those ever managing to impact us are roughly the same as the chances of you ever managing to gather up enough courage to talk to that cute girl next door from atop your solid-gold BattleMech.
If you ever meet a woman who's impressed with your bat'leth skills, it's probably time to start worrying.
But the thing with the universe is that it's kind of a largish place. However sophisticated our current equipment may seem, it's still the equivalent of shining a cereal-box flashlight into the ocean to try to spot the bottom. So whenever new technology enters the game, new data enters the equation, and we have to revise our appropriate terror levels for it. For instance, the new Pan-STARRS telescope system has, within the past five months alone, found no less than 19 completely unknown asteroids that pose a potential danger to Earth. And these have been buzzing around a mere 7.5 million kilometers away. Universally speaking, that's not on our doorstep -- that's right in our goddamn living room, ransacking our drinks cabinet and making offhand remarks about our place looking really flammable and how "It would be a shame if anything bad happened to it."
"How about Earth? They're loaded. Send over a couple of asteroids to rough up the joint."