ASTR 101 Chapter Notes - Chapter 5: Oceanic Crust, Planetary Migration, Kuiper Belt
5 Sep 2016
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Earth is only known planetary object where substantial bodies of liquid water exists at the surface. Earth"s interior heat and heat from sun should have boiled off the water on young earth, suggesting water came again later when planet was cooling. Finding the origins of water can give hints to how and when life began. Dust and minerals, turned into small, dry objects near the sun. Outer solar system, gas and water turned into large gaseous planets or icy clumps. Zone separating hot and cold regions = snow line = somewhere near asteroid belt. Suspected impacting comets were main objects that filled the seas, but was soon ruled out after finding out the hydrogen in the water in comets had only about the hydrogen-to-deuterium ratio as the water in earth"s oceans. Speculated some asteroids began as a mixture of ice and rock, then ice melted and reacted to form hydrated minerals.
