DART mission: How NASA hit the bullseye

Little asteroids strike the Earth's atmosphere every single day. It's the big ones we worry about, as depicted in such Hollywood extravaganzas as "Armageddon" and "Don't Look Up."

"I've never been able to sit still watching any of the asteroid movies and not just want to get up and walk away," said MIT professor Richard Binzel. In addition to writing the book on asteroids, he also invented the Torino scale, a 10-point danger scale for asteroids.

"All the objects we know of today reside at zero or one, which simply means they're so small that they don't matter, or that we know for sure there's no impact possibility," Binzel said.