Earth and Other Planets

1
Earth and Other Planets

• Chapter 16

Great Idea Earth, one of the planets that orbit
the Sun, formed 4.5 billion years ago from a
great cloud of dust.
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Chapter Outline

• The Formation of the Solar System
• Exploring the Solar System

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The Formation of the Solar System
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Clues to the Origin of the Solar System

• Solar system
• Objects gravitationally bound to Sun
• Deduction of origin
• Observations
• Earth
• Space

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Clue 1 Planetary Orbits

• Features of solar system
• All planets orbit in same direction
• Orbits in same plane
• Most rotate in direction of orbit

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Clue 2 Distribution of Mass

• Most material within Sun
• Two types of planets
• Terrestrial planets
• Jovian planets
• Other objects
• Moons, asteroids, comets

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The Nebular Hypothesis

• Nebular Hypothesis
• Cloud of dust and gas
• 99 H and He
• Collapse of nebula
• Planetary orbits
• Clumping of matter
• Planetesimals
• Temperature

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The Formation of Earth

• Planetesimals
• Combined to form earth
• Great bombardment
• Meteors
• Growth of planet
• 20 metric tons per day

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Differentiation

• Differentiation
• Heat from collisions
• Dense material sank to center
• Lighter material rose to surface
• Structure
• Core
• Mantle
• Crust

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The Formation of the Moon

• Big Splash
• Large object impacted earth
• Parts of mantle blown into orbit
• Moon formed from this material

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Planetary Idiosyncracies

• Cratering
• Mercury, Mars, Moon
• None on earth
• weathering
• Rotation
• Venus
• Earths axis
• Uranus

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The Evolution of Planetary Atmospheres

• Earths atmosphere
• Early
• Outgassing
• Atmosphere was N2, CO2, H2, H2O
• Gravitational escape
• Living organisms

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Exploring the Solar System
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The Inner Solar System

• Mercury, Venus, Mars
• Mercury and Venus too hot for life
• Mars Exploration
• Multiple missions
• Found evidence of water

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The Outer Solar System

• Jupiter, Saturn, Uranus, Neptune
• Layered structure
• No solid surface
• Jupiter
• Comet Shoemaker-Levy
• Galileo spacecraft
• Saturn
• Cassini spacecraft

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Moons and Rings of the Outer Planets

• Moons
• Io
• Europa
• Titan
• Rings
• Ice and rock

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Pluto

• Pluto
• Outermost planet
• .3 of earths mass
• Three moons
• Formation
• Captured comet or asteroid
• Still open to question

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A Tenth Planet?

• Xena
• Orbits sun every 560 years
• One moon
• Larger than Pluto

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Asteroids, Comets, and Meteors

• Asteroids
• Small rocky bodies
• Orbit sun
• Most in belt between Mars and Jupiter
• Comets
• Dirty snowballs
• Orbit outside Pluto
• Oort cloud
• Kuiper belt
• Halleys Comet
• Stardust and Deep Impact missions
• Meteoroids, Meteors, and Meteorites
• Meteor showers
• Original solar system material