Chapter 8c Jovian Planet Systems

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Chapter 8cJovian Planet Systems
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8.3 Jovian Planet Rings
Our Goals for Learning What are Saturns rings
like? Why do the jovian planets have rings?
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What are Saturns rings like?

• They are made up of numerous, tiny individual
  particles
• They orbit over Saturns equator
• They are very thin

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Earth-based view
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Spacecraft view
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Artists interpretation of a close-up view
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Saturns rings

• Many particles of ice and dust orbit Saturn.
• Many particle collisions cause the rings to be
  very thin (tens of meters!)
• Gap moons and orbital resonances create the
  effect of rings and gaps.

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Why do the jovian planets have rings?

• They formed from dust created in impacts on moons
  orbiting those planets

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How do we know?

• Rings arent leftover from planet formation-- the
  particles are too small to have survived this
  long.
• There must be a continuous replacement of tiny
  particles.
• The most likely source is impacts with the jovian
  moons.

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Implications

• Jovian planets all have rings because they
  possess many small moons close-in
• Impacts on these moons are random
• Saturns incredible rings may be an accident of
  our time

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What have we learned?

• What are Saturns rings like?
• Saturns rings are made up of countless
  individual particles, each orbiting Saturn
  independently like a tiny moon. The rings lie in
  Saturns equatorial plane, and they are extremely
  thin.

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What have we learned?

• Why do the jovian planets have rings?
• Ring particles probably come from the dismantling
  of small moons formed in the disks of gas that
  surrounded the jovian planets billions of years
  ago. Small ring particles come from countless
  tiny impacts on the surfaces of these moons,
  while larger ones come from impacts that shatter
  the moons.