Two different types of aurorae were observed simultaneously above Mars for the first time, thanks to solar storms that began on August 27.
The light show was studied by the Mars Atmosphere and Volatile Evolution (MAVEN), a satellite that has orbited Mars since 2014 to study its upper atmosphere.
“We have so much to learn about the atmosphere and how solar storms affect the Red Planet,” said Shannon Curry, MAVEN’s principal investigator at the University of California—Berkeley, in a statement.
The aurorae above Earth are caused by charged electrons and protons from the Sun hitting gases in the upper atmosphere. The magnetosphere steers these particles towards the poles, while protecting Earth from the radiation of solar storms.
Mars has no magnetosphere. This makes real-time and accurate space weather forecasting critical to protecting current and future Mars missions. The MAVEN team correctly predicted when the solar storms would hit Mars.
The two types of ultraviolet aurorae (diffuse and proton) were seen on the night and day sides of Mars.
“I was so surprised to see proton aurora at the same time as diffuse aurora, because it had never happened before,” said Sumedha Gupta, a postdoctoral researcher at the University of Colorado Boulder, in a statement. “They’re both increasing with solar activity, so we hope it keeps happening!”
The day side of Mars had a proton aurora — a patchy aurora unique to the Martian skies, created in part by the end of the Martian dust storm season. These storms warm the atmosphere and push water molecules into high altitudes. Solar ultraviolet radiation breaks down the molecules and releases hydrogen atoms. Mars lights up when the solar winds hit the extra hydrogen.
This solar storm coincided with even more dynamic energetic particles penetrating deeper into the atmosphere, creating a diffuse aurora visible across the entire nightside.