2005 YU55 made a near-earth pass on November 8,9, 2011. Closest approach was about 0 hour hence the two dates. It was three hours later that skies were clear enough for me to catch it. Even then I imaged through rather thick gunk making this a processing nightmare. The asteroid was under the neck of Pegasus (north of the neck as the horse is upside down in our skies) so getting a bit low. It was about 230,000 miles from us, about the same distance as the moon. As near earth asteroids go it is fairly large at an estimated size of 360 meters (1200 feet) across. While not currently considered a threat it could do real harm if its orbit changes enough to put it on a collision course. Most changes would move it further away, however. My movie is made of 10 fifteen second exposures. So you can see it was moving very rapidly. About 6.77" of arc per second of time. The image was taken at 1.5" per pixel so it was moving more than 4 pixels per second if I'd not had the mount compensating for its motion.

14" LX200R @ f/10, L=10x15", STL-11000XM, Paramount ME