The angle of this image of Victoria Crater reveals layering at the top of the crater walls. The pattern on the floor of the crater is made of sand dunes. Tracks from NASA’s Opportunity rover can be seen on the left side of the crater. This image was taken in July 2009 by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter.

This image is of the carbon dioxide ice cap at the south pole of Mars. The pattern is formed by the ice vaporizing. Scientists think that as the ice cap melts from the bottom up, the carbon dioxide turns directly into gas. It flows beneath the ice to openings, eroding the ground below into a spiderlike network of troughs. The flowing gas also carries dust that escapes with it and settles into fan-shaped deposits on top of the ice.