Minor Members of the Solar System

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Minor Members of the Solar System

• Chapter 23, Section 4

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Asteroids

• Asteroid small rocky bodies that have been
  likened to flying mountains
• Most asteroids lie between the orbits of Mars and
  Jupiter. They have orbital periods of 3 to 6
  years.
• Some have very eccentric orbits, a few regularly
  pass Earth and our moon
• Many asteroids have irregular shapes, and some
  planetary geologists believe the asteroids are
  fragments of a broken planet (pulled apart by the
  immense gravity of Jupiter)

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Asteroid Orbits
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Comets

• Comets pieces of rocky and metallic materials
  held together by frozen gases
• Most comets travel in elongated orbits, taking
  them past Pluto and take hundreds of thousands of
  years to go around the sun.
• Coma glowing head of a comet, caused by the
  solar energy vaporizing frozen gases
• A small glowing nucleus with a diameter of only a
  few kilometers can sometimes be detected within a
  coma. As comets approach the sun, some develop a
  tail that extends for millions of kilometers.
• The tail of the comet always points away from the
  sun, this is accounted for by the solar wind and
  radiation pressure

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Comets
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Comets Tail Orientation
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Beyond the Planets

• Kuiper Belt where most short-period comets are
  thought to originate from, it is a belt of
  material orbiting outside the orbit of Neptune.
• Oort Cloud Unlike the Kuiper Belt comets, these
  comets have longer orbital periods and arent
  confined to the plane of the solar system. The
  Oort Cloud appears as a spherical shell of comets
  and other materials surrounding our solar system.

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Beyond the Planets
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Meteoroids

• Meteoroid a small solid particle that travels
  through space
• Most meteoroids originate from any one of the
  following sources (1) interplanetary debris that
  was not gravitationally swept up during the
  formation of the solar system, (2) material from
  the asteroid belt, or (3) the solid remains of
  comets that once traveled near Earths orbit
• Meteor meteoroids that enter Earths atmosphere
  and burn up, a shooting star
• The light that we see is caused by the friction
  between the meteor and the air
• Meteorite a meteoroid that reaches Earths
  surface
• A few meteorites have blasted out craters on
  Earths surface

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Meteoroids
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World Map of Major Impact Structures
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The Age of the Solar System

• How did scientists determine the age of the Solar
  System?
• They use radiometric dating to determine that the
  oldest meteorites found on Earth formed more than
  4.54 billion years ago
• Scientists believe that the composition of these
  meteorites is similar to the composition of other
  materials in the inner solar system during its
  formation
• The oldest moon rocks are believed to be 4.5
  billion years old
• The oldest known Earth rocks are found in Canada
  4 billion years old

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Age of the Solar System
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Assignment

• Read Chapter 23, Section 4 (pg. 660-664)
• Do Section 23.4 Assessment 1-6 (pg. 664)