ASTR 170B1 Lecture Notes - Lecture 13: Solar Wind, Orbital Period, Runaway Greenhouse Effect
30 Oct 2018
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OCTOBER 8, 2018
• Rocky stuff, not is water
• Ice line, or waterline---- makes the rocky stuff when hot makes rocks
• Venus spins backwards
• Earth versus Mars versus Venus
o Atmosphere is different from mars and venus b/c venus and mars has carbon
dioxide in the atmosphere while earth has little carbon dioxide but mainly
hydrogen
o Atmosphere comes from when first made of the planet
o Primordial atmosphere
o Secondary atmosphere- crashing planets into each other, and all heat creates
energy and hot enough to make a circular planet
o Venus and mars are deserts, hardly any water
▪ EARTH
• 170,000x as much CO2 bound in limestones and shells and
dissolving in seawater as it has in the atmosphere. We release all
CO2, then will be like Venus, a thick atmosphere and a huge
greenhouse effect.
• Earth's atmosphere is highly modified, but things that could be in
the atmosphere have not disappeared. We could get them back
under the right circumstances
• EXAMPLE: heat earth up---> less CO2 in ocean water---> more in
atmosphere---->
▪ MARS
• We can see and count Martian volcanoes. (HUGE) can calculate
how much CO2 and water that should be there. Should have an
atmosphere 400x as dense as it is today and should have lots of
water. That thick atmosphere should make things warmer, so ought
to be lakes oceans, etc.
• Where did the atmosphere go?
o A SMALL amount is frozen out in the polar caps
o Some is bound to rocks
o Some water might be underground---- evidence exist
• Most of it was destroyed by solar wind particles and by UV light.
Mars cooled off (inside) fast. No more liquid rocks moving around
no more magnetic field, no more protection from solar wind. No
more addition of atmosphere by volcanoes. Mars has no ozone
layer to protect it from UV light
• Mars atmosphere is GONE, some of it is hidden
▪ Venus
• Still has thick CO2 atmosphere, but no water, can not have oceans
cause to hot. So the water was a gas in atmosphere. The water was
broken to constituents parts by solar wind and by UV light. Slowly
the water disappeared.
