Mars might be the Red Planet, but its atmosphere glows green.
The effect is called airglow (or dayglow or nightglow, depending on the hour), and it occurs on Earth, too. While it shares some similarities with the northern lights (or aurora) here on our planet, it’s a different phenomenon with different causes. Nightglow, in particular, “occurs when two oxygen atoms combine to form an oxygen molecule,” according to ESA.
Scientists have suspected Mars to have airglow for some 40 years, but the first observation only occurred a decade ago by ESA’s Mars Express orbiter, which detected the phenomenon in the infrared spectrum. Then, in 2020, scientists observed the phenomenon in visible light using TGO, but in Martian daylight rather than at night. Now, we’ve seen the phenomenon at night via TGO.
“These new observations are unexpected and interesting for future journeys to the Red Planet,” ULiège planetologist Jean-Claude Gérard,” said in an ESA statement. “The intensity of the night glow in the polar regions is such that simple and relatively inexpensive instruments in Martian orbit could map and monitor atmospheric flows.
A future ESA mission could carry a camera for global imaging. In addition, the emission is sufficiently intense to be observable during the polar night by future astronauts in orbit or from the Martian ground’.
This article originally appeared here and was republished with permission.