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AST101H1 Lecture Notes - Planetary Science, Volcanism

Astronomy & Astrophysics
Course Code
Michael Reid

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Comparative planetology
Active vs inactive geology
Active: earth, venus very similar in composition, size and shape (only surfaces
Inactive: mars, mercury, moon none similar
Main difference between active and inactive geology: their size (they are larger)
Heat: 3 ways in, 3 ways out
Accretion: smash stuff into it
- Mainly happened in the early solar system
- Transfer thermal energy to heat
- Heat goes mainly in the crust
Differentiation: making those heavy stuff sink into the interior, giving up potential
gravitational energy in the form of heat
- Heavy stuff sinks to middle, lighter stuff rises to surface
- Mainly happened when planets were young
Radioactivity: radioactive atoms decay and produce energy
- Can continue for billions of years
- When first comes together (the planet) it binds all elements together and
many of them are radioactive because they came from supernova; once all
the elements are incorporated into a planet they sit there and decay and
release their energy at different rates and times
- Takes longer for planet to decay if larger
3 ways to cool a planet
- Convection: heat is carried by hot material moving to a cooler area, eg.
o Eg. hot water at bottom of pot and starts to expand where the cold
sinks to the bottom and then get heated itself
- Conduction: heat is transferred by contact
o eg. when you touch a hot surface
o heat flows between layers by touch
- Radiation: energy escapes as light, heat is carried away by electromagnetic
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