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Generating a Magnetic Field

  1. Aug 9, 2012 #1
    So solid planets do not generate a magnetic field. Planets that are at least partially liquid do because they have differential rotation. I don't understand this, there is some basic concept that I'm missing. I don't even know what question to ask.
     
  2. jcsd
  3. Aug 9, 2012 #2

    Simon Bridge

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    To get a magnetic field on the scale of a planet you need a net electric current.
    The physical process is quite complicated...
    http://en.wikipedia.org/wiki/Earth's_magnetic_field#Physical_origin
    ... look up "geodynamo" and "dynamo theory".
    http://en.wikipedia.org/wiki/Geodynamo

    Oversimplified - the fluid arts can carry an electric current while the solid planets are insulators right through. For a solid planet's rotation to give you a magnetic field there has to be an uneven charge distribution through the planet.
     
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