The wind paints

A Piece of Mars: For the last few billion years, the wind has (by far) moved more sediment around on Mars than any other geological process. Not tectonics, volcanism, fluvial activity, or impact cratering (although a case has been made for glacial activity). Here’s yet one more swipe at the ground, scouring off bright dust to reveal darker terrain underneath. (HiRISE ESP_044511_2005, NASA/JPL/Univ. of Arizona)