Chapter 9: The Outer Planets

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Chapter 9 The Outer Planets

• Dr. Michelle Arnold
• October 14, 2009

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Jupiter

• Formed after the terrestrial planets
• More dust to collect!
• Formed from rock, iron and ices (water, ammonia
  and methane)
• Collected a primary (hydrogen) atmosphere from
  the accretion disk
• Kept its primary atmosphere
• Larger gravity of the planet due to larger mass
• Weaker solar winds, further from the Sun
• Jupiters composition is very similar to the
  Suns (mostly hydrogen)
• Not large enough for the hydrogen to ignite and
  form a star

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Jupiter cont.

• Most likely no solid portion
• Hydrogen atmosphere
• Liquid metallic hydrogen sea
• More dense liquid core
• Strong magnetic field
• Metallic hydrogen and rotates once every 10 h!
• 20 000x greater than Earths
• Great red spot
• Large storm on Jupiter
• Galileo first saw with his telescope

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Jupiter cont.
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Jupiter cont.
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Jupiter cont.

• Jupiters ring
• Image from Voyager

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Jupiter cont.

• Many moons (63?)
• Galilean moons 4 largest
• Io active volcanoes
• Tidal forces from Jupiter and Europa
• Europa ice, possible water (and life?) below
• Ganymede big ice rock!
• Callisto big ice rock

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Saturn

• Formed similar to Jupiter
• Saturn formed after Jupiter, and the solar winds
  had already blown away some of the hydrogen gas
  in the disk before Saturn collected it
• Inner liquid core (rocks, iron and ices) about
  same size as Jupiter
• Liquid metallic hydrogen and gaseous hydrogen
  atmospheres are smaller than Jupiter
• Strong magnetic field

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Saturn cont.

• Density 0.7 g/cm3
• It would float in water!

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Saturn cont.

• Rings
• Particles of dust and ice
• Most likely remains of a recently destroyed moon,
  comet or asteroid
• All four giant planets have rings, Saturns most
  visible
• Rings are thin, disks

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Saturn cont.
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Saturn cont.
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Saturn cont.

• Many moons
• Enceladus Cassini mission (arrived in 2004) has
  found that Enceladus has a surface of water ice
• Deformations indicate that the ice may be resting
  on a liquid interior
• Titan largest moon
• Voyager found its thick atmosphere is mostly
  nitrogen, with sig. amounts of methane (carbon!)
• Cassini sent the Huygens probe to surface and
  takes radio photoes of the surface from above
• Surface has methane and ethane lakes!

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Titans Surface