Chapter 29 The Solar System

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Chapter 29 The Solar System

• Ch. 29.2
• The Inner Planets

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• The four inner planets are known as the
  terrestrial planets because they are similar to
  earth.
• Formed close to the sun (and its heat), so most
  light elements with low boiling points were
  driven off.
• Consist mostly of solid rock with metal cores.

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• Lack of rings.
• Zero to two moons.
• Solid surfaces--have impact craters.

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Mercury

• Closest to the sun.
• Shortest orbit period88 days.
• Slow rotation on its axis59 days.
• Hard to see due to its being obscured by the
  suns light. Always low in the sky.
• No moons.
• Mariner 10 in 1974 and 1979 revealed heavily
  cratered surface.

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• Evidence of volcanism.
• Long lines of high cliffs due to wrinkles in the
  crust when the once-molten core cooled and
  shrank.
• Very thin atmospheredue to weak gravity and high
  temp. of gas molecules.
• Very large daily temp. range427 C at day, and
  -173 C at night.
• Weak magnetic field.

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Venus

• Second planet from sun.
• Orbit is 225 days.
• Slow opposite rotation once every 243 days.
  Day is longer than year (Sun rises in west, sets
  in east!).
• No moons.
• Almost same mass, size, and density as earth.

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• Very hotcloser to sun and thick insulating
  atmosphere. Avg. surface temperature is 464 C.
• Atmospheric pressure is 90 times the atmospheric
  pressure on earth.
• Atmosphere is 96 carbon dioxide.
• Clouds of sulfuric acid.
• Basalt and granite surface.

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Earth

• Third planet from the sun.
• Orbit period 365.24 days.
• Rotates once every 23 hours, 56 minutes.
• 5th largest planet one moon.
• Very geologically active.
• Temperature just right for liquid water to exist.

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• Most carbon dioxide absorbed by oceans, so heat
  escapes into space instead of building up.
• Average temp. is 14 C.
• Photosynthesis increased atmospheric oxygen.

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Mars

• Fourth planet.
• Orbital period is 687 days.
• Martian day is 24 hours, 37 minutes.
• Seasons, due to tilt of axis similar to Earths.
• Two small moons.
• Geologically active lava flows and large
  volcanoes.

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• Olympus Mons is the largest volcano in the solar
  system3 times higher than Mt. Everest.
• Deep canyons, one as long as the United States
  (Valles Marineris)
• Low atmospheric pressure doesnt allow liquid
  water to exist, but evidence of flowing water in
  the past.

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Valles Marineris
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• 20 C at equator in summer, and -130 C at polar
  ice caps in winter.
• Possible liquid water beneath the surface in some
  places.