The last time a space rock as big came as close to Earth was in 1976, although astronomers did not know about the flyby at the time. The next known approach of an asteroid this large will be in 2028.
Scientists working with the 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, Calif., have generated a short movie clip of asteroid 2005 YU55. The images were generated from data collected at Goldstone on Nov. 7, 2011, between 11:24 a.m. and 1:35 p.m. PST (2:24 p.m. and 4:35 p.m. EST). They are the highest-resolution images ever generated by radar of a near-Earth object.
NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called “Spaceguard,” discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.