Asteroid YU-55, also written as 2005 YU55, is a potentially hazardous asteroid approximately 400 meters (1,300 feet) in diameter. It was discovered on 28 December 2005 by Robert S. McMillan at Steward Observatory, Kitt Peak. On 8 November 2011 it passed 0.85 lunar distances (324,600 kilometers or 201,700 miles) from the Earth. This is the closest known approach by an asteroid with an absolute magnitude this bright since 2010 XC15 (H = 21.4) approached within 0.5 lunar distances in 1976. (read more) (video clip)