Natural color view of Ganymede from the Galileo spacecraft during its first encounter with the satellite. North is to the top of the picture and the Sun illuminates the surface from the right. The dark areas are the older, more heavily cratered regions and the light areas are younger, tectonically deformed regions. The brownish-gray color is due to mixtures of rocky materials and ice.
Bright spots are geologically recent impact craters and their ejecta.
The finest details that can be discerned in this picture are about 13.4 kilometers across. Galileo scientists are in the process of calibrating and validating this data. The full digital image necessary for scientific analysis will be released within one year of receipt of this orbit's last data. For more information on the Galileo mission, you can link to the original at the NASA-JPL server.