Comets, Meteors, and Asteroids

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Comets, Meteors, and Asteroids
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Structure of a Comet
Ion Tail
Dust Tail
Coma
To Sun
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Comet Structure

• Nucleus
• 10 km Dirty Snowball
• Coma
• Cloud of evaporated ices and ions
• may be 100,000 km in diameter
• Tail
• Always points away from Sun
• Solar Wind and Radiation Pressure

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The Oort Cloud

• In 1950 Jan Oort noticed that
• no comet has been observed with an orbit that
  indicates that it came from interstellar space,
• there is a strong tendency for aphelia (the
  furthest point away from the Sun) of long period
  comet orbits to lie at a distance of about 50,000
  AU, and
• there is no preferential direction from which
  comets come.

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The Oort Cloud
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Comet Halley
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Bayeaux TapestryNorman Invasion of 1066
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Comet Halley 1910

• Pope Callixtus III excommunicated Halley's Comet
  in 1456
• In 1910, charlatans sold "comet pills"

Orbit
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Comet Nucleus
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Comet of 1577
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Hyakutake
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Hale-Bopp (Spring 1997)
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Comet West
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The Cause of Meteor Showers
P55/Tempel-Tuttle
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Why After Midnight is Best
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Shower Radiant
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The 1833 storm
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The 1966 storm
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1997 Leonids from Orbit
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Two Showers for Halley
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Sporadic Meteors
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Barringers Crater
Iron Meteorite 100 feet across and 70,000 tons
Slammed into the Earth at about 43,000
mph Arizona desert near Flagstaff 40,000 years
ago. Barringer Crater is 4,100 feet wide and 571
feet deep.
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Other Impact Craters
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Tunguska, 1908
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How Much Damage?
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Asteroids
Apollo
Trojans
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Ida - Dactyl
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Gaspra
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Kirkwood Gaps
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Asteroids Elsewhere
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Sedna
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End of Section