Airglow and Aurora in the Atmospheres of Venus and Mars

We compare measurements and models of the luminosity that originates in the Martian and Venusian atmospheres, including dayglow, nightglow and aurora. Most of the emission features considered appear in the ultraviolet and visible regions of the spectrum and arise from electronic transitions of thermospheric species. Some of the dayglow features discussed include the O 1304 and 1356 Å multiplets, the red and green lines and the 2972 Å line of atomic oxygen, the fourth positive and Cameron bands of CO, the Fox-Duffendack-Barker bands and ultraviolet doublet of CO2+, the 1.27μm infrared atmospheric band of O2, the atomic carbon 1561 and 1657 Å lines, and the Lyman alpha line of atomic hydrogen. Nightglow emissions included the NO delta and gamma bands, the O2 Herzberg II bands, and the red and green lines of atomic oxygen. Spatially and temporally variable intensities of the oxygen 1304 and 1356 Å lines have been observed on the nightside of Venus and have been labeled “auroral”, that is, ascribed to electron precipitation. Only a future aeronomy mission to Mars could unequivocally determine whether such emissions are present on the nightside of Mars