Caption: 
These MAVEN images show the sudden appearance of a bright aurora on Mars during a solar storm in September 2017. The purple-white color scheme shows the intensity of ultraviolet light seen on Mars' night side before (left) and during (right) the event. SwRI’s Radiation Assessment Detector confirmed the data on the surface from aboard NASA’s Curiosity rover. 

Credit: 
Image courtesy of NASA/Univ. of Colorado 