Bright scars on a darker surface testify to a long history of impacts on
Jupiter's moon Callisto in this image of Callisto from NASA's Galileo
spacecraft.
The picture, taken in May 2001, is the only complete global color image of
Callisto obtained by Galileo, which began orbiting Jupiter in 1995. Of Jupiter's
four largest moons, Callisto orbits farthest from the giant planet.
Callisto's surface is uniformly cratered but is not uniform in color or
brightness. Brighter areas are mainly water ice and the darker
areas are highly eroded, ice-poor material.