Astronomy Picture of the Day

Explanation: Last week, an asteroid approached unusually close to the Earth. Passing well outside the orbit of our Moon, Asteroid 1998 WT24 posed no danger, but became bright enough to see with binoculars and to track with radar. Pictured above, the kilometer-sized asteroid was imaged crossing the sky on December 14, two days before closest approach. Every few years, an asteroid will actually pass inside the orbit of the Moon. Large impact features on the Earth are testaments to asteroids or comets that actually impacted the Earth in the distant past. Astronomers continue to discover, track, and study potentially hazardous asteroids with a goal of making planet Earth a safer place.