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Lecture 15

AST101H1 Lecture Notes - Lecture 15: Carbon Cycle, Thermostat, Earth Mass

Astronomy & Astrophysics
Course Code
Dan Dolderman

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interiors and atmospheres of the terrestrial planets
clicker quiz
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)
aging planets
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
iclicker quiz
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
iclicker quiz
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 cycle
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
clicker quiz
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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