The 100-foot-wide (30-m) dust devil curves slightly, pushed by a westerly breeze. Tracks from previous whirlwinds are also visible in the Mars twister picture, showing up as streaks on the Red Planet's surface. The dust devil's shadow can also clearly be seen in the photo.
Dust devils occur on both Earth and Mars. They are spinning columns of air, made visible by the dirt they suck up off the ground.