This aerial view of an alien landscape was taken by the Mars Reconnaissance Orbiter near Mars’ North Pole. The dark streaks on the northern Martian dunes are the result of avalanches, caused by the seasonal melting of carbon dioxide ice. The dunes are made of dark basalt sand, covered with a thin layer of pinkish iron oxide dust. When the dry ice melts, the sand beneath becomes dislodged causing it to flow down the side of the dunes, creating the tendril-like effect. Just left of centre you can see a cloud of iron oxide thrown up by one of the Martian avalanches.
— John Davis