Data from the NASA MAVEN orbiter shows the Red Planet 'glowing green' at night due to upper atmosphere chemical reactions. The nightglow phenomenon is not visible to the naked eye and can only be seen as ultraviolet light imaged by MAVEN's Imaging Ultraviolet Spectrograph instrument. During the Martian night the upper atmosphere pulsates in ultraviolet light given off as nitrogen and oxygen atoms combine to form nitric oxide. The discovery could help researchers forecast weather on Mars for the first crewed missions expected sometime in the next decade.