A piece of Mars: Ripples form endless chevrons in this 600×450 m (0.37×0.30 mi) scene. It’s really the crest of a dune that connects all the vertices in the chevrons, making that straight line that runs nearly vertical through the center. Wind from the south (bottom) is deflected by this crest and other local topography just out of the scene. This pattern has been there for at least 3 Mars years. How long will it last? (HiRISE ESP_013785_1300, NASA/JPL/Univ. of Arizona)