Outline for Today

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Denizens of the Solar System I Terrestrial
Planets
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General Properties of the Solar System

• There are two classes of planets
• The Terrestrial planets are small, solid bodies
  (rocks iron) in the inner part of the Solar
  System.
• The Jovian planets are hydrogen-rich gas giants
  in the outer part of the Solar System.
• Each planet is in an elliptical, almost-circular
  orbit in the plane of the ecliptic, moving
  west-to-east in the sky relative to the fixed
  stars.
• Between Mars and Jupiter there are large numbers
  of small asteroids.
• Outside the orbit of Neptune is the Kuiper Belt
  of comets.
• Far beyond Pluto is the Oort Cloud of comets.

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Relative Sizes of the Sun and Planets
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The Planets
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Mercury
Mercury notes many impact craters (looks like
the Moon) very dense (mostly iron) rotation
period exactly 2/3 of its orbital period (a
resonance) very large day/night temperature
difference no atmosphere no moon origin of
twilight zone
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The Planets
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The Planets
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Venus
optical
ultraviolet
radar map
Venus notes similar in size and mass to earth
extremely thick CO2 atmosphere sulfuric acid
clouds hottest planet in the Solar System
little temperature variance evidence of
volcanoes on surface rotates slowly backwards
some impact craters no moon
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The Planets
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The Planets
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Earth and Moon
Earth/Moon notes Double planet (Moon similar
in size to Earth) extremely different surface
conditions Moon keeps one same side towards
Earth at all times nature of the dark side of
the Moon
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Earth
Earth notes liquid water on surface very dense
(mostly iron) thick atmosphere of N2 and O2
(trace amounts of CO2) a few impact craters
small difference in day/night temperature
evidence of volcanoes and tectonic activity
water vapor clouds
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The Moon
Moon notes many impact craters less dense than
Earth (mostly rock) no atmosphere large
day/night temperature difference evidence of
past lava flows (only on side facing Earth) no
present volcanoes or tectonic activity
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The Planets
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The Planets
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Mars
Mars notes medium density (rocks) polar ice
caps (H2O and CO2) thin CO2 atmosphere moderate
daytime/night temperature changes some impact
craters large canyons and volcanoes evidence
for old river beds dust storms two small moons
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Mars
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Mars
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Mars
Deimos and Phobos
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The Planets
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Terrestrial Planets Questions

• Name some of the defining differences between
  terrestrial and Jovian (gas giant) planets.
• Which planet has a day and seasons somewhat like
  Earths?
• Why is Earth sometimes called a binary planet?

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Terrestrial Planets  Summary

• Planets orbit in and near the ecliptic plane, in
  nearly circular (but technically, elliptical)
  orbits
• Terrestrial (rocky) planets
• Mercury Small, Moon-sized, hot
• Venus Hottest planetary surface greenhouse
  effect
• Earth Binary planet, liquid water, thick
  atmosphere
• Mars Small planet with days seasons, once had
  water