This image shows a small rayed impact crater, about 160 meters (530 feet) in diameter, in the Tharsis region in the northern hemisphere of Mars.
Relatively recent impacts form rays of ejecta that spray out radially from the crater. In addition to relatively fine material, large boulders and smaller secondary craters are visible in the rays surrounding this crater.
Secondary craters are recognized by their shallow depths (in comparison to primary craters), irregular shapes, and appearance in clusters and linear chains.Written by: Maria Banks (15 May 2008)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_008011_1975
Image: NASA/JPL/University of Arizona