Notes
Slide Show
Outline
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Remnants of Rock and Ice
  • Remnants of Rock and Ice:
  • Asteroids, Comets, and Pluto
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Remnants from Birth
  • Comets, Asteroids and Meteorites carry the history of our solar system encoded in their compositions, locations, and numbers.


  • Asteroid:
    • a rocky leftover planetesimal orbiting the Sun.

  • Comet:
    • an icy leftover planetesimal orbiting the Sun-regardless of its size or whether or not it has a tail.
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"Meteor:"
  • Meteor:
    • a flash of light in the  sky caused by a  particle entering the atmosphere, whether the particle  comes from an asteroid or a comet.

  • Meteorite:
    • any piece of rock that fell to the ground from the sky, whether from an asteroid, a comet, or even another planet.
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Asteroids
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"The main Asteroid Belt lies..."
  • The main Asteroid Belt lies between 2.2 and 3.3 AU from the Sun.


  • Origin and Evolution of the  Asteroid belt:
    • The Asteroid belt probably formed as a result of orbital resonance. Resonance occurs whenever one object’s orbital period is a simple ratio of another object’s period.


    • These resonances with Jupiter probably prevented a planet from ever forming in the region of the Asteroid Belt.
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"Another effect of the resonance..."
  • Another effect of the resonance is to form gaps in the orbits of the Asteroids as they orbit the Sun.


  • These are called the Kirkwood Gaps.
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See SFA Observatory
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Meteorites
  • Primitive Meteorites: Most primitive meteorites are composed of rocky minerals with an important difference from Earth rocks.
  • The Primitive Meteorites are our best source of information about conditions in the solar nebula.
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Processed Meteorites
  • A smaller group of meteorites appears to have undergone substantial change since the formation of the solar system.


  • These “Processed Meteorites” apparently were once part of a larger object that modified the original material into another form.
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Origin of Meteorites
  • Carbon –rich meteorites came from the outer portion of the asteroid belt.           (> 3AU)


  • Carbon – poor meteorites formed in the inner warmer part of the asteroid belt.


  • The processed meteorites have compositions similar to the cores, mantles, or crusts  of the terrestrial worlds. These are fragments of the terrestrial worlds.
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"Processed meteorites with basaltic compositions..."
  • Processed meteorites with basaltic compositions must have come from lava flows.
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Comets
  • Icy Planetesimals that have been left over from the formation of the Solar System.
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Comets exist as bare nuclei over most of their orbits and grow a coma and tails only when they  approach the Sun
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Pluto
  • Pluto was discovered in 1930 by an American Astronomer named Clyde Tombaugh.


  • Pluto has long been seen to be a misfit among the planets, fitting into neither the terrestrail nor the jovian category.


  • It has a 248 year orbit that is unusually elliptical and significantly tilted relative to the ecliptic.


  • Pluto has a moon – Charon.
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Cosmic Collisions
  • The numbers of small bodies orbiting the solar system have diminished significantly since the days of early bombardment, when most impact craters were formed.


  • However, there are still plenty of fragments left and collisions between these fragments and the planets still occur on occasion.
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The End.
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Comet Shoemaker-Levy 9
  • Was shatter by Jupiter’s gravity in 1992.
  • All pieces hit Jupiter in the summer of 1994 leaving dark impact scars.
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Minor Body Comparisons
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Earth Impacts and Near Misses
  • Arizona Meteor Crater
    • measures 1 mile across
    • from an impact 50,000 years ago
    • by a 50 meter meteoroid
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The End...