AST101H1 Lecture Notes - Lecture 15: Carbon Cycle, Thermostat, Earth Mass
DepartmentAstronomy & Astrophysics
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interiors and atmospheres of the terrestrial planets
•Q: a small potato and large potato in oven for 40 minutes, which cools faster?
•A: small potato – cooks faster and cools faster (release heat rapidly)
earth and venus - thin crust on outside, large molten magma mantles
mars, mercury, moon - thick lithosphere (does not undergo plate tectonics)
•bigger or younger planet = geologically active
moon's dark spots
•dark because moon use to have thin lithosphere (impacts smashed the lithosphere)
•younger planet = thin lithosphere
•Q: an earth mass planet was found and it orbits closer to its start than earth, if its the same
age as earth, you'd expect it to have:
•A: about the same number of volcanoes as earth
•where do our atmosphere and oceans come from?
•Q: Which of these is NOT a source?
•A: earth's gravity pulling in gas from the solar nebula
◦earth is not big enough, not enough gravity (needs to be 10x bigger than its mass)
earths atmosphere (good for life)
•opaque to infrared radiation (due to water, carbon dioxide and methane molecules)
earth - +/- 30 degree difference with/without greenhouse gas
venus – (highly effected by greenhouse) 520 degree difference = inhospitable place
•carbon dioxide is the element that changes the most
•reason why the temperature stays reasonably constant (earths thermostat)
•less carbon dioxide = easier heat can escape
•too warm = remove carbon dioxide from atmosphere
•Q: if the temperature of earth dropped a little, what would happen?
•A: the oceans would absorb less CO2 and the temperature would go back up
•reduce pressure = water cannot be liquid
•low pressure of atmosphere = ice or steam
•no long term liquid water on surface of mars
•higher pressure, high atmosphere = livable planet – mars before
mars vs. earth
•mostly based on size
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