Dunes in the Western Nereidum Montes, on Arrakis-- I mean Mars. The Nereidum Montes mountain range stretches over 1000 kilometres and features mountains three to four thousands metres high. Photo: NASA/JPL/University of Arizona
On the far left (or bottom) dark sand covers the ground, while the center shows a transition to a dune field. On the far right (or top) a transition is made to a much lighter surface, likely containing a larger amount of ice.
Victoria Crater, an impact crater at Meridiani Planum, near the equator of Mars. The crater is approximately 800 meters (half a mile) in diameter. Image: High Resolution Imaging Science Experiment (HiRISE) on Mars Reconnaissance Orbiter, NASA
Martian Crater Rich in Opal - The CRISM imaging spectrometer on board the Mars Reconnaissance Orbiter identified the minerals present in this crater south of Baldet Crater. Among them is a form of hydrated silica, better known as the gemstone opal.
A piece of Mars: This is the edge of the northern polar cap on Mars. At the top is the icy surface, abruptly cut by a cliff. The cliff wall shows many layers of different materials -- the darker ones are old dunes. How cool is it to know that the polar ice cap on another planet is sitting on what used to be an enormous sand sea? It's like looking at limestone and shale on mountains here on Earth an imagining them once being at the bottom of an ocean. It blows my mind. (HiRISE…