Blue Dune on Mars

Sand dunes often accumulate in the floors of craters. In this region of Lyot Crater, NASA’s Mars Reconnaissance Orbiter (MRO) shows a field of classic barchan dunes on Jan. 24, 2018. This particular dune, appearing like turquoise blue in enhanced color, is made of finer material and/or has a different composition than the surrounding.

Source: Once in a Blue Dune