Astr 150 – Midterm Review Fall 2006
Chelsea MacLeod
Best way to study: Read through your notes while going through the lecture slides/notes online,
practice old midterm questions and email me if you have a question, and study past labs. Also
might be a good idea to make sure you know how to answer each question(s) of the day.
Topics to study:
I. General solar system info:
 The six numbers
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Most abundant elements in solar system
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Density (and compressed vs. uncompressed), albedo, moment of inertia
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Five stages of planetary evolution
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Geological activity scales with size
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Gravity (study homework assignment!) and Kepler’s Laws (online tutorial)
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What two factors determine whether a planet has an atmosphere
o
II. The inner solar system:
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Land features: Impacts, volcanism, tectonics
o Tectonics (endogenetic):
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Straight Rilles (faults), wrinkle ridges
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plate tectonics
o Volcanism (endogenetic):
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duration scales with size of planet
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Sinuous Rilles (lava channels/tubes), lava flows (mare)
o Impacts (exogenetic):
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three types: simple, complex, impact basins
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ground folding out; rocks closest to rim are deepest and oldest
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use to age surface (crater counting  crater density plots)
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R plots: use to characterize population of craters; shows fraction of total
area covered by craters of different sizes
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Crater density plots and R plots are similar among small worlds (moon,
Mercury, and Mars) and similar among larger worlds (Earth and Venus)
(Why?)
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The Moon:
o negligible atmosphere, uniform density
o characteristics of lunar mare and lunar highlands
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age, albedo, types of rocks found in each (study Moon Rocks lab)
o Moon origin: 4 theories
o why we love the moon (it stabilizes our tilt)
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Mercury:
o negligible atmosphere
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o large iron core => scarps
o Caloris Basin; hilly and lineated terrain on opposite side of Caloris Basin
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Mars:
o Thin cold CO2 atmosphere => low thermal inertia
o splash craters
o Tharsis range: huge volcanoes due to low gravity and lack of plate tectonics
o Evidence for water in Mars’ past: hematite spheres, layered sedimentary rock, and
weathered rock
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=> thicker past atmosphere
Venus:
o Thick hot CO2 atmosphere => high thermal inertia
o young surface; use radar to image
o Coronae (blobs): result from mantel plumes. There are also antiplumes
o Distribution of craters uniform over entire surface => all same age
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Earth:
o has been hit most in solar system
o craters get worn away in many ways
o KT event
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Evidence: Iridium, shock lines in minerals
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Global impact
Terrestrial atmospheres:
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o can be blown away by huge impacts
o secondary atmosphere: Earth, Venus, and Mars
o How did Venus lose H2O, and Earth lose CO2?
o Greenhouse effect
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