Astronomy Picture of the Day

Explanation: Since April 30, the robotic NEAR-Shoemaker spacecraft has been orbiting only 31 miles from asteroid Eros. Cruising over the asteroid's north and south poles at a leisurely 7 miles per hour, the spacecraft completes an orbit once every 1.2 earth days. This dramatic horizon view recorded by the spacecraft's camera on May 18 spans about 0.8 miles and reveals features as small as 13 feet across. Emphasized by long, harsh shadows produced by the low sun angle, the rolling surface of Eros is seen to be strewn with boulders and craters with a range of sizes. The jagged-looking boulder near the picture center is over 190 feet tall. While gathering sharp pictures of Eros' surface, experimenters will also take advantage of the close orbit to explore the asteroid's surface composition and internal structure, and search for a magnetic field.