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Martian missions have shown that the landscapes and features of the red planet are strikingly similar to those on Earth; among the most easily identifiable are sand dunes. These images from Earth and Mars are almost indistinguishable from one another, showing beautiful barchan and star-shaped dunes forming on both planets. A key difference is evident in the frosty edges of Mars’s dunes: on Mars, the dunes are found in areas where temperatures can plummet to -150 degrees Celsius.

Dunes form when grains of sand are blown around by winds. Subtle variations in the landscape allow grains to settle in sheltered zones away from the wind, creating small sand patches. These patches grow, trapping more sand until recognisable dune features are formed. Barchan dunes develop when the wind blows consistently in one direction, whereas star dunes form where the wind blows from multiple directions. Geologists use their knowledge about landscapes on Earth to help them understand environments and processes on Mars and other planets.