Two-Faced Moon

Saturn's moon Iapetus is one of the oddballs of the solar system. One hemisphere is almost completely white, while the opposite hemisphere is as dark as charcoal (part of the dark side is at the right of this image from the Cassini spacecraft). The bright side is coated with ice, while the dark side may be coated with material that was blasted off the surfaces of other moons, then swept up by Iapetus as it orbited Saturn. The moon is 912 miles (1,468 km) in diameter. The most prominent feature in this image is a 280-mile (450-km) impact basin at bottom. [NASA/JPL/SSI]