September 3, 2008--Telltale tracks on Mars's Gusev Crater were created by dust devils that picked up lighter-colored dust and exposed the planet's darker basaltic substrate.

The HiRISE spacecraft captured the image on July 22 while orbiting above the red planet.

Dust devils are created when solar radiation warms the Martian surface and forces heated air to rise. When that air cools in the atmosphere, it descends and produces a convective circulation with a powerful suction effect.