Class 3 : Craters in the solar
system.
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Recap last class…
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Patterns in the solar system.
Theory for solar system formation.
How do we test this theory?
Variety of surfaces in the solar system
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Classifying surfaces.
The processes at work.
I : Classification of surfaces
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Can classify surfaces in the Solar
System into the following groups:
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Processes that are relevant:
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Heavily cratered.
Mildly cratered.
Blotchy/linear features.
Shrouded by an atmosphere.
Impacts by asteroids, comets etc.
Volcanic activity.
Atmospheric erosion.
Let’s look at this in some more detail.
II : Heavily cratered bodies
Far side of
The Moon
Two kinds of terrain: highlands and maria
The Moon & Mercury
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Very little or no atmosphere…
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All incoming meteors hit the surface
(different from Earth where small objects
burn or break up).
Once made, craters stay (any erosion
processes happen very very slowly).
Located in the inner solar system
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More rocky (outer moons are icy), so
craters survive longer.
More debris to cause craters.
Lunar Terrain
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Highlands
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Several kilometers higher.
Heavily cratered.
4 – 4.4 billion years old.
Aluminum rich rock (light colored).
Maria (“seas”)
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Younger (3.2 – 3.9 billion years old).
Iron rich rock (dark color).
Old Lava flows (like Hawaii on Earth today).
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Another sign of lava flows… lunar rilles are
believed to be remains of old lava flows.
III : Volcanism in the solar
system
Io – the most active volcanic region in the Solar System
Examples…
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Io
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Very smooth surface – no craters or rilles.
Thought to be a very young surface – lava
has filled all craters and valleys.
Strong stretching/pulling by Jupiter heats
interior and causes volcanic activity.
Mars
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Possesses some giant dead volcanoes (e.g.
Olympus Mons… 27km high, 600km wide).
Example of a crater not caused by impacts.
IV : The outer moons – ice
geology at work.
Europa
Surface ice sheet occasionally seems to break and float
around on an underlying liquid water ocean