Astronomy Picture of the Day

Explanation: Last month the NEAR Shoemaker spacecraft swooped closer to Eros, orbiting only 22 miles (36 kilometers) from the center of the asteroid. These two images taken on July 19 (left) and July 24 (right) reveal the diminutive world's pocked and mottled surface in amazing detail, showing features as small as 19 feet (6 meters) across. Eros is thought to be a primordial, undifferentiated asteroid based on X-ray and gamma-ray studies of its surface composition. In the left picture, its surface layer or regolith is seen to be laced with bright and dark regions while in the right hand image dark regolith appears to have filled in some crater floors. The left and right images span an area about 2,600 feet (800 meters) and 3,000 ft (900 meters) wide respectively. On July 31, NEAR Shoemaker returned to its familiar 31 mile (50 kilometer) orbit, circling Eros serenely at about 6 miles per hour.