Asteroid 2012 DA14 will pass Earth this evening in a very near miss. It is the size of an olympic swimming pool and will pass the Earth at a distance of just 27,700 km. This is even closer than our geostationary satellites! For comparison the Moon orbits at a distance of around 384,400 km!
If you would like to try to spot the asteroid you will need a pair of binoculars or a small telescope. Even though it passes very close to us it will still only reach magnitude 8 making it invisible to the naked eye. Through a pair of binoculars it will look like a bright point of light moving quickly through the field of view.
You can spot it in the northeastern sky from about 8pm and it will pass through the familiar big dipper at about 9.30pm.