Close Approach By Asteroid 2012 BX34
An anonymous reader writes with news that asteroid 2012 BX34, 11 meters wide, is in the process of passing within 60,000km of Earth — about a fifth of the distance between the Earth and the Moon. At that size, the asteroid would pose no danger even if it hit the Earth's atmosphere.
also of interest, a 10 meter metal (e.g. iron-nickel) asteroid will have big fragments that will hit the ground, for example the one that hit Sikhote-Alin mountains in Siberia in February 1947, 150 tons of fragments hit the ground and one of them weighed 1.7 tons!
The issue is we can only tell when one is about a day out. Many times we can only see them as they are leaving, not aproaching. It is actually a fairly common occorance. You can see them at http://www.spaceweather.com/. Since the begniing of the year there have been 5 that have come close enough to actually be of note.