Space exploration, through telescopes, probes, rovers and other devices on the ground often provide images capable of capturing anyone's imagination, sometimes in a slightly deceptive way. This is what happened this week with an image published by the European Space AgencyESA for its acronym in English, of the surface of Mars, in which what appears to be a large number of spiders on it. Martian spiders? The explanation is much more prosaic, a simple case of pareidolia.
The photograph, taken by the probe ExoMars TGO in the south polar region of Mars, shows a series of natural geological formations that take place with the arrival of spring in this part of the red planet and that can be confused with the silhouette of a multitude of arthropods.
As explained by the ESA, this phenomenon occurs 'when the spring sun falls on the layers of carbon dioxide deposited during the dark winter months. Sunlight causes the carbon dioxide ice at the bottom of the layer to turn into a gas, which subsequently accumulates and breaks up the overlying ice sheets. The gas is released in the Martian spring, dragging dark material to the surface and breaking through layers of ice up to a meter thick'.
This gas makes its way forming geysers before falling again and settling on the Martian surface, which creates dark spots between 45 meters and a kilometer wide. As a consequence of this process, those spider-shaped patterns appear which can be seen along hills and plateaus of Mars.
The ESA probe ExoMars TGO, acronym for Trace Gas Orbiter, orbits Mars from 2016 and is part of the ExoMars program that in 2028 plans to carry the first European rover, the Rosalind Franklin, to this planet. The published image was taken while flying over what is nicknamed 'Inca City' from Mars. This is a geological formation that, in another case of pareidolia, resembles the ruins of an ancient city.
Pareidolia is the process by which the brain perceives certain familiar patterns or shapes, such as faces or objects, in random stimuli. For example, when certain shapes are identified in the clouds.
In the so-called Inca City, the 'walls' are part of the perimeter of a Martian crater and their formation could be due to the petrification of sand dunes or be the result of magma or sand seeping through the surface, as explained by the ESA. But seen from orbit, it looks like what it looks like.