The old joke about the dinosaurs going extinct because they didn't have a space program may be overselling the need for one. It turns out you can probably divert some of the more threatening asteroids with nothing more than the products of a nuclear weapons program. But it doesn't work the way you probably think it does.

Exploding a nuclear bomb above a huge asteroid could vaporize its surface using X-rays, pushing the space rock away from Earth.

Scientists have found nuclear weapons could actually help deflect an incoming cosmic impact — not by blowing an asteroid up, but by showering it with X-ray radiation.