Asteroid DA14 is due to fly past Earth in a few hours. It's 50 metres across and will pass just 17,100 miles above our heads. Although there is no danger of a collision, it's still passing much closer than any other known asteroid and closer than many man made satellites.
NASA will be doing a live stream of the asteroid as it passes us by, so don't despair if it won't be visible from your area. The stream will begin at 19:00 GMT/14:00 EST/11:00 PST. You'll be able to watch it here: http://www.ustream.tv/nasajpl2
For more info on the flyby, visit this NASA page: http://www.nasa.gov/topics/solarsystem/features/asteroidflyby.html