Asteroid 2005 YU55 will pass closer to the Earth than the orbit of the Moon on November 8th, 2011. At over 1300 feet in length, this one would cause some serious damage if it struck the Earth. This is the nearest pass of a know space rock since 1976 and there won’t be another (fingers crossed) until 2028.
2005 YU55 will be able to be seen by a telescope with an aperture of 6 inches or larger, so plenty of data will be collected as it passes.
The strange object was discovered on January 6 by the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey, which is funded by the United States Air Force and NASA and located in New Mexico.
Generally, comets follow elliptical orbits that get close in to the sun and grow long gaseous and dusty tails as ices sublimate off their solid cores. Asteroids are mostly in more circular orbits and with a high density of them living between the orbits of the planets Mars and Jupiter in the asteroid belt.
Several other comet/asteroid hybrids have been reported over the years, but are still not completely understood by astronomers.
This previously unknown object may be on a high speed collision course with another object in the belt. Astronomers can see debris from previous impacts, but have never seen a collision as it happens.