Spring Thaw in Northwestern Planum Australe

Planum Australe--the Plains of the South. Patchy frost lingers late into Martian spring in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle view from November 25, 1999. Spring would give way to summer in only 1 month, on December 25, 1999. The surfaces underneath the frost have different properties--some get warmer while others stay cold--thus causing frost to linger on colder surfaces and sublime away from warmer surfaces, leaving the dazzling, almost psychedelic pattern seen at the center of this image. Circular features in this view are old craters formed by meteor impact. The brightest patches within most of these circles are fields of sand dunes covered by frost.