The Trace Gas Orbiter spacecraft that has been orbiting Mars for several years has detected a green nightglow in the Red Planet's atmosphere via the onboard Nadir and Occultation for Mars Discovery (NOMAD) spectrometer.
Nightglow, also known as airglow, is essentially an emission of light by a planet’s atmosphere.
In Mars’ case, this emission occurs “due to the recombination of oxygen atoms created in the summer atmosphere and transported by winds to high winter latitudes, at altitudes of 40 to 60 km,” according to Lauriane Soret, one of the authors of the study on the subject that has been published in the journal Nature Astronomy last week.
“This O2 nightglow should be observable from a Martian orbiter as well as from the Martian surface with the naked eye under clear sky conditions,” the researchers wrote, adding that “these observations pave the way to future global observations of the Martian atmospheric circulation with simpler lower-cost instrumentation.”
According to a statement shared on the European Space Agency’s website, the nightglow “serves as a tracer of atmospheric processes” and “can provide a wealth of information about the composition and dynamics of a region of the atmosphere difficult to measure, as well as the oxygen density." It can also help determine “how energy is deposited by both the Sun’s light and the solar wind.”