The dune, which is painted in turquoise blue, to distinguish it from the surrounding area, which differs from it in the composition of the materials, stands out in the field thanks to the reaction of the frozen carbon dioxide gas that took off in the spring
Sand dunes accumulate on Mars mainly on crater soils. In the area of Lyot Crater, the Mars Reconnaissance Orbiter (MRO) spacecraft photographed a field of classically structured vertebrae on January 24, 2018. The image was captured using the high-resolution HiRISE camera mounted on the spacecraft.
A little south of the group of dunes is a large dune with a complex structure. This dune, which appears blue-turquoise due to the use of artificial dyes, is made of finer sand grains or its composition is different from that of its surroundings. The scale of the map is about 25 centimeters per pixel, the image is positioned with its north side up.
At that time, spring was in full swing in the northern hemisphere of Mars. "During the winter, snow and ice continuously covered the dunes," explains NASA. "Unlike the Earth, the snow and ice are not made of water but of carbon dioxide, known to us as dry ice. The gas reacts with the dunes and creates wave-like formations along the dunes
When the spring sun warms the dune, the gas frozen inside the dune escapes into the atmosphere and rises (going from a solid state directly to a gaseous accumulation state), carrying dark sand from the bottom of the dunes and often creating beautiful patterns like this one.
For information on NASA's "Picture of the Day" website
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