The Strange little moon Iapetus. click for larger. Image credit: NASA/JPL/Space Science Institute

This Cassini image of Iapetus, a moon of Saturn,  shows how beat up it is.  Iapetus is a small moon, at 912 miles (1468 km) in diameter, now just look at those large impact craters; the larger craters are almost a third the diameter of the planet at 280 miles (450 km) wide.

Another interesting feature of the moon is the dark areas.  The dark areas occur on the leading hemisphere while the trailing hemisphere is nice and bright.  One of the Cassini pages dedicated to Iapetus (click here) speculates the dark areas are “composed of nitrogen-bearing organic compounds called cyanides, hydrated minerals and other carbonaceous minerals–appears to coat equator-facing slopes and crater floors. The distribution of this material and variations in the color of the bright material across the trailing hemisphere will be crucial clues to understanding the origin of Iapetus’ peculiar bright-dark dual personality.”

See the image on the source page here.