The Terrestrial Planets

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The Terrestrial Planets
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Exploration of Mercury
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Mercury Half-Mapped
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Mercurys Orbit

• Fairly eccentric with e0.21
• Perihelion distance 0.31 AU
• Aphelion distance 0.47 AU
• Resonance
• So Mercury rotates 3 times for every 2 orbits
  around the Sun
• This is a tidal effect from the Sun

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The Mercurian Day
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Advance of Mercurys Orbit
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General Properties of Mercury

• Temperature
• 100 K at night to 700 K by day
• Magnetic Field
• Surprisingly strong at 0.5 of Earths
• Magnetic field and high average density suggest a
  large iron core
• Atmosphere
• None
• Interior
• Large iron core - 1/3 by volume, extending to
  about 70 of radius

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Degas
Impact crater about 45 km wide Imaged by
the Mariner 10 flybys
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Surface Effects
Scarps are seen on Mercury. Useful for relative
dating and history of the surface.
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Caloris Basin
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Interior of Mercury
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Origin Model for Mercury