Captioned Image Spotlight: Active Dunes in Wirtz CraterThese…

Captioned Image Spotlight: Active Dunes in Wirtz Crater

These gorgeous dunes are likely active, with ripples on their upwind slopes and dark streaks on their downwind slopes forming and changing due to wind-driven sand motion.

This motion will also keep the dune brink (the edge between the two slopes) and bottom edges sharply defined. The dark lines and squiggles on the dune slope are formed by passing dust devils.

NASA/JPL/University of Arizona