CHED 1672 |
| The planets in our solar system display a range of volatile inventories and atmospheric compositions. Earth's atmosphere is oxygen-rich, those of Venus and Mars are mainly carbon dioxide, and the gas giant planets have hydrogen-rich atmospheres. I review the atmospheric compositions and volatile inventories of the planets. Atmospheric origin is then described. The terrestrial planets (Venus, Earth, and Mars) have secondary atmospheres that originated by the outgassing of volatile-rich material during and/or after planetary accretion. The gas giant planets (Jupiter, Saturn, Uranus, and Neptune) have primary atmospheres that were captured from the solar nebula. Some of the important chemical cycles that presently operate in planetary atmospheres are illustrated. This discussion shows that thermochemistry controls the atmospheric composition on Venus and in the deep atmospheres of the gas giant planets. In contrast, photochemistry dominates atmospheric chemistry on Mars and in the upper atmospheres of the gas giants. Biochemistry is the key process on Earth, with photochemistry also playing an important role. Some speculations about atmospheric chemistry and composition on extrasolar Earth-like planets are also presented. |
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Chemical Evolution, Chemical Change Across Space and Time
9:00 AM-11:55 AM, Wednesday, March 28, 2007 McCormick Place North -- Room N227A, Level 2, Oral
Division of Chemical Education |