The Dotted Dunes of Mars. As spring dawns on the Northern Hemisphere of Mars, dunes of sand near the poles begin to defrost. Thinner regions of ice typically thaw first revealing sand whose darkness soaks in sunlight and accelerates the thaw.
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