 "In pics: Stunning images of snowy dunes on Mars captured by Nasa")
NASA has released a stunning picture of dunes on the surface of Mars with snow and ice on ridges.
It was spring in the Northern hemisphere when this image was taken by the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter, NASA said.
Over the winter, snow and ice inexorably covered the dunes. But unlike on Earth, this snow and ice is carbon dioxide, better known to us as dry ice.
When the sun starts shining on it in the spring, the ice on the smooth surface of the dune cracks and escaping gas carries dark sand out from the dune below, often creating beautiful patterns.
On the rough surface between the dunes, frost is trapped behind small sheltered ridges.
The image was captured in May and NASA released it on Thursday.