Green night glow detected in the atmosphere of Mars

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Researchers recently detected a green night glow in the atmosphere of Mars. This is the first time that such a phenomenon has been observed on another planet.

On Earth, some lucky observers can observe the northern lights at high altitudes. These night shows are produced by energetic electrons from interplanetary space that “hit” the oxygen molecules in the upper atmosphere. Dawn, however, is just one of the ways planets can light up.

Certain atmospheres, including that of Earth, indeed shine constantly during the day (daytime glow) and at night (nighttime glow), while sunlight interacts with certain atoms and other molecules.

These two lights are driven by slightly different mechanisms. “The“ night glow ”, on the other hand, occurs when the exploded molecules recombine, while the“ day glow ”is produced when the sunlight directly excites atoms and molecules such as nitrogen and l ‘oxygen’, explains ESA.

On Earth, the daytime glow is almost impossible to discern, while the nighttime glow is only visible from very high altitudes. It is for this reason that only a few astronauts aboard the International Space Station (ISS) have had the chance to appreciate it.

The Martian atmosphere tinged with green

A team of researchers from the University of Liège (Belgium), led by Jean-Claude Gérard, announces that they have detected not a “daylight” but a “nightlight”, tinging the Martian atmosphere with emerald green. It is the first time that this phenomenon has been directly observed on another planet.

To do this, the researchers relied on the Nadir and NOMAD instruments of the Trace Gas Orbiter (TGO), equipped with ultraviolet-visible spectrometers (UVIS). They then studied the air of the red planet from a special angle from April to December 2019, imitating the perspective we might have from the ISS, positioned above Earth.

The researchers then scanned the atmosphere of Mars at altitudes between 20 to 400 kilometers. They then detected this green glow at all altitudes, although it was much more marked at about 80 km from the ground.

According to their analyzes, this nocturnal glow here is mainly caused by the decomposition of carbon dioxide, which constitutes 95% of the thin atmosphere of Mars, into carbon monoxide and oxygen.

Finally, note that the TGO, in orbit around the red planet since October 2016, is part of the Russian-European program ExoMars. He plans to send a rover (Rosalind Franklin) in 2022 to search for traces of past life.

As a reminder, this rover was supposed to take off this summer, but technical problems with the parachutes did not allow us to take advantage of this launch window.