Download GM/2r

Exam Review
Atmospheres Summary
• Surface temperature depends on solar distance,
albedo, atmosphere (greenhouse effect)
• Scale height and lapse rate are controlled by bulk
properties of atmosphere (and gravity)
• Terrestrial planetary atmospheres are not primordial
– affected by loss and outgassing
• Coriolis effect organizes circulation into “cells” and is
responsible for bands seen on giant planets
• Isotopic fractionation is a good signal of atmospheric
loss due to Jeans escape
• Significant volatile quantities may be present in the
interiors of terrestrial planets
Key Concepts
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Albedo and opacity
Greenhouse effect
Snowball Earth
Scale height H = RT/gm
Lapse rate
Tropopause
Coriolis effect 2 w v sin(q)
Hadley cell
Geostrophic balance
Jeans escape
Urey reaction
Outgassing
Orbits Summary
• Elliptical orbits (Kepler’s laws) are explained by
Newton’s inverse square law for gravity
• In the absence of external torques, orbital angular
momentum is conserved (e.g. Earth-Moon system)
• Orbital energy depends on distance from primary
• Tides arise because gravitational attraction varies
from one side of a body to the other
• Tides can rip a body apart if it gets too close to the
primary (Roche limit)
• Tidal torques result in synchronous satellite orbits
• Diurnal tides (for eccentric orbit) can lead to heating
and volcanism (Io, Enceladus)
Key Concepts
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Angular frequency
Angular momentum
Tides & diurnal tides
Roche limit
Synchronous satellite
Laplace resonance
GM=r3w2
I   mr   r dm
2
L  Iw
E= - GM/2r
2
Satellites Summary
• For icy satellites, main source of energy is tides – link
between orbital and geological evolution
• Some show present-day geological activity
(Enceladus, Europa, Io, Triton)
• Many show ancient geological activity
• Oceans are quite common – habitability
• Titan is unusual because it has an atmosphere and an
active “hydrosphere” (liquid methane)
• Likely to be targets for future spacecraft missions
Comets Summary
• Comets are dirty snowballs with a dark crust
• They provide samples of (hopefully)
primordial, volatile-rich solar nebula material
• SP comets come from the Kuiper Belt
• LP comets come from the Oort Cloud
• The architecture of the Kuiper Belt is probably
a result of Jupiter, Saturn and Neptune moving
around early in their history!
Asteroids key concepts
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Asteroid belt, Kirkwood gaps
Lagrangian points
Near earth objects
Space weathering
Some geologic observations of asteroids
Vesta vs. Ceres
Chondrules and chondrite meteorites
HED meteorites and Vesta