ASTRO-110 Lecture Notes - Lecture 20: Thermostat, Lithosphere, Interstellar Travel
9 Sep 2020
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Document Summary
A zone in which the surface temperature of a planet could allow it to have abundant liquid water on the surface. E. g. , the moon is in the hz, but does not have surface water. Earth"s temperature remained cool enough for liquid oceans to form. Oceans dissolve atmospheric co2, enabling carbon to be trapped in rocks. Co2 content of oceans = 60 atmosphere"s. Co2 content of rocks = 170,000 atmosphere"s. Surface can not be seen from the earth. Without the atmospheric greenhouse effect, surface temperature would be. Runaway greenhouse effect would account for why venus has so little water. Uv dissociation of h2o molecules at altitude. H-atoms lost to space, unable to form water any more. Insufficient h2o to dissolve co2 into oceans, rocks. Co2 builds up from outgassing, rock decomposition. Lithosphere continuously loses water over planets" lifetime. Sufficient greenhouse warming for an earth-like planet (<1. 7 au) Possible solutions to habitability of earth >500 myr from now.
