Ultraviolet glow reveals Mars weather patterns

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) orbiter has mapped seasonal wind patterns at the red planet’s equator and poles using the ultraviolet nightglow produced by atmospheric reactions (J. Geophys. Res.: Space Phys. 2020, DOI: 10.1029/2019JA027318). Solar radiation splits CO₂ and N₂ molecules in Mars’s atmosphere. When N and O atoms combine in the cooler, denser night air to make NO, they release a UV photon. The atmospheric waves and tidal action MAVEN observed mostly match scientists’ existing models of Mars’s atmosphere and its seasonal variations. But the satellite did find stronger NO signals at the equator than expected, and a surprising spiral wave at the south pole (shown).