Theoretical studies of the photochemistry of planetary atmospheres (including those of the ancient and modern earth) are based on physical and chemical premises common to all. Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperature have produced vastly different atmospheres, however. Some of these similarities and differences are described in this paper, which is based in part on invited presentations at the Fall 1980 AGU Meeting.
Ozone is a constituent of earth's atmosphere; it is also found in the atmosphere of Mars. Sulfur dioxide is a constituent of the atmosphere of Venus; it is also found in the atmosphere of Io. Methane may have been a constituent of the earth's ancient atmosphere; it is found today in the atmospheres of Titan, Jupiter, and Saturn. Can chemists explain these similarities between systems so different in their physical properties?