Today, the planet Earth will get a fly-by from an asteroid known as 2012 DA14 that's about half the size of a football field. At 2:25 Eastern Time, the asteroid will come within 17,000 miles of Earth, flying over Indonesia. It's the closest recorded brush with an object of this size.
It's a good thing it's not getting any closer. In 1908, an asteroid about the same size hit Russia and knocked over millions of trees over an 820 square mile area. Scientists say another asteroid, about six-miles in diameter, hit Earth about 66 million years ago and wiped out the dinosaurs.
If you're concerned about such things, you can rest a bit easier. The United Nations has been working on a plan against such space threats for a dozen years and suggests that if any future orbiting objects put earth in jeopardy, they'll put together a space mission to destroy any asteroid headed for Earth. Sounds like a Bruce Willis movie.