With the help of an American spacecraft, it was possible to photograph a Martian crater, in which an unusual pattern is visible.
In the crater called Airy-0 (the diameter of the formation is about 500 m), furrows are located at the bottom in such a way that from above it resembles a fingerprint print.
In fact, these are sand dunes, known as “eolian ridges”. They are covered with a layer of dust. The composition of the latter mainly includes hematite, which is the reason for the gray tint.
The main Airy crater was discovered in the century before last. Scientists began to use it as a marker of the prime meridian, since this crater is perfectly distinguishable in the eyepiece of a weak telescope. When the Martian landscapes began to be photographed in detail, they decided to take Airy-0, located inside Airy, as a mark.