Chapter 7 The Terrestrial Worlds

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Chapter 7The Terrestrial Worlds
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Mercurycraterssmooth plainscliffs
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Mooncraterssmooth plains
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Venusvolcanoesfew craters
Radar view of a twin-peaked volcano
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Earthvolcanoescratersmountainsriverbeds
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Marssome cratersvolcanoesancient riverbeds
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Terrestrial Planet Interiors
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Lithosphere

• A planets outer layer of cool, rigid rock is
  called the lithosphere.
• It floats on the warmer, softer rock that lies
  beneath.

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How Did They Get This Way?Differentiation

• Gravity pulls high-density material to center
• Lower-density material rises to surface
• Material ends up separated by density

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Sources of Internal Heat

• Gravitational potential energy of accreting
  planetesimals
• Differentiation
• Radioactivity

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Cooling of Interior

• Convection transports heat as hot material rises
  and cool material falls
• Conduction transfers heat from hot material to
  cool material
• Radiation sends energy into space

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Tectonics
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Seafloor Recycling
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Continental Motion
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Types of Lava and Volcanoes
Runny lava makes flat lava plains.
Slightly thicker lava makes broad shield
volcanoes.
Thickest lava makes steep stratovolcanoes.
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Moon

• Volcanoes flooded lunar craters
• lunar maria

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Same thing on Mercury
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Water on Mars
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Storms on Mars
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Low-lying regions may once have had oceans.
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Today, most water lies frozen underground (blue
regions) Recent gulley formation?
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Erosion on Venus

• Photos of rocks taken by lander show little
  erosion

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Tectonics on Mercury

• Long cliffs indicate that Mercury shrank early in
  its history.

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The Greenhouse Effect
Which Molecules are Greenhouse Gases?
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Runaway Greenhouse Effect
More evaporation, stronger greenhouse effect
Greater heat, more evaporation