The sky is figuratively falling potentially someday.
1 in 10 chance of big asteroid hitting us this century
NASA has a tough time dealing with that, but it is tricky business.
here is their website on that
Asteroid 2004 FH, a 30- meter wide object, was discovered only 3 days before it came within 26000 miles of Earth, closer than the farthest satellites
And here is how to figure out, mathematically, how scared you should be.

Proposed maxims:
the complete destruction of the planet by an asteroid would not, in and of itself, be a negative thing.
deep impact was way better than armageddon