Chapter%2028%20Notes

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Chapter 28 Notes

• Our Solar System

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Our Solar System
3
The Inner Planets (and Pluto)
4
All the Planets (and Pluto)
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The Planets and the Sun (and Pluto)
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Formation of the Solar System

• Nebular Theory
• Interstellar cloud contracts and spins
• Dense center begins nuclear fusion (sun)
• Remaining material forms planetesimals and then
  planets

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Historical Solar System Models

• Geocentric (Earth-centered) model
• One problem was how to explain retrograde motion
• Copernicus heliocentric model
• 1543, Polish scientist
• Planets (including Earth) orbit the Sun in
  circular orbits
• Supporting evidence collected by Tycho Brahe

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Keplers laws of planetary motion

• Johannes Kepler inherited Tychos data after his
  unexpected death.

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Galileo

• First person to use a telescope to observe the
  sky
• Discovered moons orbiting Jupiter
• Also observed sun spots, phases of Venus, and
  Moon craters

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Newton and Gravity

• Newtons discovery of the law of universal
  gravitation provided an explanation for the
  heliocentric model of the solar system

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Zone 1 Inner Planets

• Terrestrial Earth-like
• Small
• Composed of rock (high density)
• Close to the Sun
• Few or no moons
• No rings

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Mercury

• Smallest
• Closest to the Sun
• No moons
• No atmosphere
• Cratered like the Moon
• 1 orbit 1.5 rotations (2 years 3 days)

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Venus

• No moons
• Earths twin in size
• Rotates backwards
• 1 day 243 Earth days
• Very high CO2 concentration in the atmosphere
  causes super greenhouse effect
• Surface temperature of 464?C!!
• Can be seen as a bright morning or evening star

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Earth

• One moon
• Tectonically active
• O2 in atmosphere
• Water exists in all 3 phases
• Mild greenhouse effect to keep the planet warm
  enough for life

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Mars

• The red planet
• CO2 atmosphere
• 2 moons (Phobos and Deimos)
• Has seasons like Earth, but a year is twice as
  long
• Largest volcano in the solar system Olympus Mons
• Once had liquid water, has polar CO2 ice caps

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Outer Planets

• Gas giants or Jovian Jupiter-like
• Large
• Low density
• Lots of moons
• All have ring systems
• Far from the Sun

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Jupiter

• Largest planet
• Banded appearance
• Great red spot
• Faint ring system
• 4 large moons, more than 60 total
• Rapid rotation (10 hours 1 day) shortest day
  of all the planets

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Saturn

• Famous for ring system
• More than 55 moons
• Density lower than water
• Largest moon, Titan, has an atmosphere of
  nitrogen and methane
• Another moon, Enceladus, shows evidence of
  geologic activity

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Uranus

• Discovered in 1781
• Rotational axis is 98?
• At least 27 moons
• Rings are dark and nearly invisible
• Appears blue because of the way it reflects light

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Neptune

• Discovered 1846
• 13 moons
• Distinctive clouds and belts
• Predicted before it was discovered
• 6 rings composed of dust particles
• Largest moon, Triton, orbits backwards

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Other Solar System Objects

• Dwarf planets
• Asteroids
• Kuiper belt objects (KBOs)
• Comets (the Oort cloud)