Mars Proton Aurora

MAVEN’s Imaging Ultraviolet Spectrograph observes the atmosphere of Mars, making images of neutral hydrogen and proton aurora simultaneously (left). Observations under normal conditions show hydrogen on the disk and in the extended atmosphere of the planet from a vantage point on the nightside (middle). Proton aurora is visible as a significant brightening on the limb and disk (right); with the contribution of neutral hydrogen subtracted, the distribution of proton aurora is revealed, showing that it peaks in brightness just off the Martian disk as energetic neutrals slam into the atmosphere.