volcanoes and heating

• When Io closer to Jupiter, tidal force stronger, Io squeezed
  • when further away, it is un-squeezed
• surface deformed by 100 m every orbit!
  • friction converts deformation to heat
  • interior hot enough to melt rocks and sulphur, leading to volcanic activity
• whole surface renewed in a few years!

• Scientist calculated the tidal heating of Io and predicted the molten nature of the interior just before the Voyager spacecraft arrived at Jupiter in 1979
  • predictions are much more impressive than post-dictions
  • Io also pulls on Europa resonantly
    • gravitational forces equal and opposite
    • Europa’s orbit also made slightly elliptical
    • tidal force of Jupiter will heat interior
      • liquid water below ice surface
      • active renewal of surface

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