SALVATORE BABONES replied 16th Jan '14:
Actually, there is no one protecting us!
The United Nations has no "Space Forces" and there is no one protecting us from asteroids, though there is an international asteroid monitoring effort. Monitoring is one thing; protecting is something else entirely. Only in science fiction movies do we have any way to deflect or blow up an approaching asteroid. Probably our best defense is simply that the Earth is a big place, mostly ocean and desert, so when a meteor does hit it usually doesn't hit people. Even a huge meteor strike would be unlikely to harm many people directly, and as for the chance that it might change the climate, well . . . we're already doing that without any help from outer space!