Patches of Snow
The North Pole of Mars is surrounded by a vast sea of sand dunes. In this dune field, the dunes are covered by a seasonal cap of dry ice in the winter.
In early Martian summer, at the time we acquired this image, the dunes are almost free of their seasonal ice cover. Only pockets of ice protected in the shade most of the day remain.
NASA/JPL/University of Arizona (333 km above the surface; enhanced color is less than 1 km across.)