Callisto, the 4th and most distant Galilean moon. takes 16.7 days to complete an orbit of Jupiter.
Its icy surface is more cratered than the inner moons.
The image on the left shows the moon in natural colour.
The false colours in the right image, produced with infrared, green and violet filters,
emphasise crater ejecta and other variations on the moon's surface.
Source: Planetary Photojournal - PIA01298