Download Ch. 23: “Touring Our Solar System”

Ch. 23: “Touring Our Solar
System”
23.4: “Minor Members of the Solar
System”
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The Asteroids
What are the asteroids?
a) The broken up remnants of a destroyed planet?
b) Material that never managed to form into a planet?
The current balance of opinion favors the latter, due to the existence
of stable orbits between Mars and Jupiter.
An asteroid is a small, rocky body whose diameter can range
from a few hundred kilometers to less than a kilometer. Most
lie between Mars and Jupiter and have orbital periods of 3-6
years.
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Irregular Orbits of Asteroids
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Comets
• Small body composed of chunks of rock and
metal held together by ice (water, ammonia,
methane, carbon dioxide)
• Anatomy of a comet
– Coma: glowing “head” of the comet; as comet
approaches the sun, solar winds vaporize the frozen
gases causing the nucleus to glow
– Tail: the solar wind that vaporizes the frozen gases
also blows the gas away forming a long tail (millions
of kilometers)
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Comet’s Tail Points Away from the Sun
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Some Comets
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Comets
• Comets originate in one of two locations
– Kuiper Belt: orbital area outside of Neptune
and lies in the same plane as the solar system
• Comets that originate here have very short orbital
periods (ie Halley’s comet; 76 years)
– Oort Cloud: 360 degree sphere around the
solar system
• Comets that originate here have long orbital periods
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Kuiper belt and Oort cloud
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23.4 Minor Members of the Solar System
Meteoroids
 A meteoroid is a small, solid particle that
travels through space.
 A meteor is the luminous phenomenon
observed when a meteoroid enters Earth’s
atmosphere and burns up, popularly called
a shooting star.
 A meteorite is any portion of a meteoroid
that reaches Earth’s surface.
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23.4 Minor Members of the Solar System
Meteoroids
 Most meteoroids originate from any one of
the following three sources:
(1)interplanetary debris that was not
gravitationally swept up by the planets
during the formation of the solar system,
(2)material from the asteroid belt, or
(3)the solid remains of comets that once
traveled near Earth’s orbit.
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Major Meteor Showers
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