Big green glow, not little green men seen on Mars

Space Science

Artist’s illustration of the European Space Agency’s ExoMars Trace Gas Orbiter detecting the green glow of oxygen in the Martian atmosphere. This emission, spotted on the dayside of Mars, is similar to the night glow seen around Earth’s atmosphere from space.
(Image: © ESA)

MYSTERY WIRE — Mars has an atmosphere. It’s different than the one here on Earth, but recently has shown something strangely similar to ours. The atmosphere of Mars has a distinct green glow.

It was the European Space Agency’s Trace Gas Orbiter (TGO) that spotted the glow. This is the first time this glow has been detected anywhere other than Earth. 

Study lead author Jean-Claude Gérard, of the Université de Liège in Belgium, said in a statement, “This emission has been predicted to exist at Mars for around 40 years — and, thanks to TGO, we’ve found it.”

Scientists believe it is oxygen creating the glow, similar to our northern lights, or auroras, which are generated by charged particles from the sun slamming into molecules high up in the atmosphere.

But that’s where the similarity stops. The Mars glow is hard to see, even here on Earth; observers often need an edge-on perspective to see it. This is also the reason some of the best photographs and videos of Earth’s auroras are taken from the International Space Station (ISS).

In this image, taken by astronauts aboard the International Space Station (ISS) in 2011, a green band of oxygen glow is visible over Earth’s curve. On the surface, portions of northern Africa are visible, with evening lights shining along the Nile river and its delta. (Image credit: NASA)

The green oxygen glow was found by the scientists at all altitudes between 12 miles and 250 miles in the Martian atmosphere, peaking at around 50 miles above the surface.

According to, TGO has been circling Mars since October 2016. The orbiter is part of the two-phase European-Russian ExoMars program, which plans to launch a life-hunting rover called Rosalind Franklin toward the Red Planet in 2022. (The Rosalind Franklin was originally supposed to lift off this summer, but technical issues with the spacecraft’s parachute and other systems caused the mission to miss that window.)

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