Evacuate Earth National Geographic Documentary

A planet destroying event, while certainly possible, seems much less likely than an "extinction level event" such as a large comet or asteroid impact. These have happened before, the most well known being the one that killed the dinosaurs, and are bound to happen again, sooner or later.

SciFi writers like the idea of blowing an approaching asteroid or comet to smithereens, like they tried to do in "Deep Impact," but space agencies suggest that a gentle nudge to change its trajectory a bit so that it doesn't hit the earth would be a better idea.

This documentary suggests what might be attempted if we had to start planning an escape mission today. But with any luck at all, such a mission will never be necessary. With just a little less luck, it won't be necessary for centuries or millennia, by which time space travel could be routine, taking much of the desperation out of the equation.