Turns out the Red Planet is a little more green than we thought. The ExoMars Trace Gas Orbiter (TGO) has detected a tinge of green in the atmosphere, making it the first time this aurora-like glow has been spotted around a planet other than Earth.
Here at home, green glows in the sky are caused by glowing oxygen, excited by collisions with electrons that stream into the atmosphere from solar wind. While aurora are the most dramatic examples, the sky glows almost constantly. At night it can appear green as molecules previously ripped apart by solar winds begin to recombine.
It was predicted that this same effect should be visible around other planets, but it’s hard to spot since the bright surfaces of planets can wash out the color. Now, astronomers from ESA have managed to detect it around Mars for the first time.