The Giant Planets - Jupiter, Saturn, Uranus

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The Giant Planets -Jupiter, Saturn, Uranus
Neptune
Chapter 8
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Jovian Planets Basics

• Distance 5-30 AU
• Much farther from Sun than terrestrial planets
• Much colder (100-50 K)
• Mass 10-100 Earth masses
• Much more massive than terrestrial planets
• Jupiter Saturn are similar
• Size (about 10 Earth diameters)
• Composition mostly hydrogen and helium
• Uranus Neptune are similar
• Smaller than Jupiter Saturn
• Less hydrogen and helium

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Basic Data

• Jupiter
• 318 Earth masses
• 11 Earth diameters
• density 1.3 g/cm3
• Saturn
• 95 Earth masses
• density 0.7 g/cm3
• would float!
• lowest of any planet

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Basic Data

• Uranus
• 14 Earth masses
• density 1.2 g/cm3
• diameter 36 of Jupiters
• Neptune
• 17 Earth masses
• density 1.6 g/cm3
• diameter 35 of Jupiters

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Appearance

• Jovian planets show banded appearance
• due to atmosphere
• we see only cloud tops
• Rotation quite fast (hours)
• Jupiter 10 hrs
• Saturn 11 hrs
• Uranus 17 hrs
• Neptune 16 hrs

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Clouds

• Clouds on Jupiter Saturn
• composed of ammonia ice (NH3)
• different colors
• due to differing cloud composition
• Saturns clouds deeper less visible
• Clouds on Uranus Neptune
• composed of methane (CH4)
• produces blue-green color

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Atmospheric Structure

• Temperature and pressure increase inward
• Different molecules condense at different
  altitudes
• Form cloud layers

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Winds and Weather

• Cloud Bands
• alternating E-W wind patterns
• Light zones indicate upwelling
• Dark zones indicate sinking

convection
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Winds and Weather

• Storms
• Great Red Spot on Jupiter
• has persisted for over 400 yrs
• Great Dark Spot on Neptune
• seen in 1989 by Voyager
• not seen in 1994 (by HST)

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Axial Tilt Seasons

• Jupiter
• only 3º axis tilt no real seasons
• Saturn
• 27º tilt normal seasonal variation
• Neptune
• 29º tilt similar to Saturn
• Uranus
• 98º tilt (on its side!) collision?
• extreme seasons!
• each 21 yrs long

Seasons on Uranus
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Interior Composition and Structure

• Cores rock ice
• extreme pressure
• Jupiter and Saturn
• large outer layers (H, He)
• Uranus and Neptune
• like Jupiter, Saturn with outer layers removed
• Much less hydrogen

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Summary of Jovian Planets

• Jovian planets larger, more massive than
  terrestrial
• Composition
• mostly hydrogen (H) and helium (He)
• dominated by hydrogen
• also large amounts of ices (water, ammonia,
  methane)
• Why So Large?
• basic reason is distance from sun
• cooler temps allowed ices (volatiles) to freeze

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Role of Volatiles

• Inner solar system is hot
• volatiles are gaseous not available for planet
  core formation
• planet cores
• only rock (no ice)
• smaller, less massive (1 earth mass)
• Outer solar system is cold
• volatiles are solid available for planet core
  formation
• planet cores
• both rock and ice
• bigger, more massive (10 earth masses)
• Massive cores have larger gravity can capture
  gas
• Jovian planets have massive atmospheres (lots of
  H and He)
• Terrestrial planets have minimal atmosphere
  (little H and He)