Venus%20

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Venus lite
Currently in southwest sky after sunset, (
greatest elongation of 47 degrees was Nov 3rd ),
magnitude -4.3 Stays low, reaches inferior
conjunction January 13, 2006
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Fierce Greenhouse Effect
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Rotation discovered via radar
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Retrograde rotation - unexplained
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Soviets landed probes
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Magellan radar of Maat Mons
Rises 8km High due to no plate motion (one
continental plate) Planet resurfaced about 500M
years ago
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Mercury
Note high density
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A Morning/Evening star

• Limited by maximum elongation

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.. Of 29O, maximum

• Mercury (also) reached greatest elongation east
  (24 degrees) on Nov 3rd
• Still in SSW, magnitude about -0.1
• .

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Albedos

• Mercury bright in spite of low albedo
• Albedo percent of light reflected
• Mercury dark, albedo 11 (7 for the Moon)
• Clouded planets high, 72 for Venus, half that
  for the Earth

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Transits

• Crossing between us and the Sun is a transit
• Venus and Mercury both do it
• This from the TRACE
• Venus transited June 8, 2004

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Spin-orbit resonance

• Orbit takes 88 days
• Rotation is 2/3 of this (59 days)
• 32 spin-orbit resonance, due to tidal forces at
  perihelion
• Combined, the Mercury daynight is 176 days long

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Mariner 10 composite

• Heavily cratered
• Ejecta not thrown as far as on Moon

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Scarps

• Cliffs that form along faults
• Not tectonic like on Earth
• Probably wrinkles due to impacts

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Caloris Basin

• Large circular region of impact (left side of
  this image)
• If look at opposite hemisphere

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Hilly, rough terrain opposite Caloris

• Theory

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Impact
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Magnetic field

• Magnetic field 0.5 Earths, suggests

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Interior structure

• Must have a large metal core to get high density
  without the Earths larger gravity to compress
• Large fraction of iron suggests impact origin

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like this

• Impact throws of most silicates, leaving large
  fraction of iron

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Future Missions

• NASA has the Messenger mission under way,
  launched August, 2004 , will make several flybys
  of Earth Venus before orbits Mercury in March
  of 2011
• ESA/Japan have BepiColombo in development