For all we know, right now a huge chunk of killer space rock is hurtling toward Earth and will eventually end all life as we know it. A big enough collision might even send our world hurtling out of orbit and destroy the whole damn planet! Fortunately, the universe is a pretty big place, so there is lots of “empty” space through which comets and asteroids can go hurtling about without smashing into planets. But at some point the odds are that we’ll have another Cretaceous–Paleogene Extinction Event type of impact, or one even worse. Until that happens, we can wring our hands over these close calls.