Martian fans and ribbons
Dunes creep across the red planet, pushed along by the wind, as they do on Earth.
Fans and ribbons of dark sand dunes creep across the floor of Bunge Crater on Mars in response to winds blowing from the direction at the top of the picture. The frame is about 14 kilometres wide.
This image was snapped in January 2006 by the Thermal Emission Imaging System instrument on NASA's Mars Odyssey orbiter.