Mysterious Objects in New Mars Images Aren't Swarms of Spiders, Scientists Say

Recent images from the European Space Agency (ESA) has released of the so-called “Inca City” on Mars are striking enough to give anyone a fear of spiders. However, what the images show has little to do with spiders, or the Inca Empire, for that matter.

Spiders on Mars. In late April, the ESA shared some new images of Mars where the Red Planet looks a little different than usual. Specifically, the images show a series of dark spots that bring to mind an asterisk or spider.

However, the points with intersecting lines we see in the images have nothing to do with the arthropod or the typographical symbol. They're actually geological formations caused by the arrival of spring to the planet's south pole.

CO2 geysers. According to the ESA, the formation process of the so-called “spiders” on Mars begins when the sunlight falls on layers of atmospheric carbon dioxide (CO2) that have been deposited on the planet's surface during winter. This causes the solid-state CO2 in the soil to transform into a gas. Given that the gas on the deepest layer heats up first, it eventually breaks through the upper layer, resulting in a geyser-like eruption.

The CO2 carries darker soil particles that contrast with the rest of the surface, creating these formations that can range in diameter from about 150 feet (45 meters) to roughly half a mile (1 kilometer).

TGO. ESA’s TGO (ExoMars Trace Gas Orbiter), the first part of the ExoMars program, captured the images of these formations. The ExoMars program plans to launch the first European rover, the Rosalind Franklin, to Mars in 2028.

Since 2016, the TGO has orbited the neighboring planet and studied the Martian atmosphere, analyzing its changes through the planet’s different seasons.

Inca City. Scientists have captured a new image of Mars’ south pole, revealing a geological formation known as “Inca City.” The cliffs in this formation are said to resemble the ruins of an ancient city from a distance.

Yet, their exact geological origin is still uncertain, at least according to the ESA. Some theories suggest that the formation could be the result petrified sand dunes. Others claim they could be magma or sand seeping along fractures in the Martian rock.

What we do know is that these “walls” are part of the perimeter of a crater that was formed due to impact of an asteroid on the planet’s surface.

Pareidolia. Pareidolia is a phenomenon where our brain finds patterns that it associates with recognizable elements, leading us to see familiar objects or shapes in things that are actually random or meaningless. This could explain why we might see spiders or lost cities in geological formations.

Mars’ rocks have provided many examples of pareidolia, such as the well-known “Face of Mars.” In recent years, people have seen everything from bears to doors on the planet’s surface.

Pareidolias can be much more complex, though. Sometimes, they're harmless, like seeing a smiley face in the sun. Other times, they can lead to interesting sociological phenomena, like people believing they see time travelers or deities manifesting themselves at breakfast.

Image | ESA/TGO/CaSSIS