AST 111 Lecture Notes - Lecture 22: Solar Time, Giant Planet, Double Planet
18 Dec 2020
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Document Summary
Ice ages- intervals of extremely cool temperatures. Milutin milankovich argued in 1920 that the ice ages were caused by changes in the obliquity of earth"s spin axis, and its eccentricity of orbit. Records show that the spacing between the ice ages are 44,000 and 100,00 years, which makes the milankovich effect seem accurate. However, earth has also undergone other rapid climate changes which cannot be due to the milankovich effect. It is now believed that earth"s interior was heated over 900 million years by radioactive decay of uranium and other elements. It is believed that this led to an interval of extensive volcanic activity. It is also believed that this volcanic activity resulted in the origin of earth"s atmosphere through the process of outgassing. In outgassing, volcanoes released gases from the mantle and crust, importantly water vapor (or steam), which condensed in the atmosphere and fell to form oceans.
