Quote barakn-------------------------------------------------------------
Molten metal certainly can't be a permanent magnet but it can carry a current, and currents create magnetic fields. Check out this link to an experiment using turbulent molten sodium to create a magnetic field:
http://focus.aps.org/story/v19/st3------------------------------------------------------------------------------
Many things that don't occur in nature can be produced or observed under artificial laboratory conditions... such as Fullerenes or Buckyballs, and even precipitation of sodium currents to produce magnetic fields.
Planets Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
Diameter 0.382\ 0.949\ 1\ 0.532\ 11.209\ 9.44\ 4.007\ 3.883\ 0.180
Rotation 58.65\ -243*\ 1\ 1.03\ 0.41\ 0.44\ -0.72*\ 0.72\ -6.38*
Mass 0.055\ 0.815\ 1\ 0.107\ 318\ 95\ 15\ 17\ 0.002
AU to sun 0.39\ 0.72\ 1\ 1.52\ 5.20\ 9.54\ 19.18\ 30.06\ 39.44
Gravity 0.30\ 0.9\ 1\ 0.38\ 2.64\ 0.93\ 0.89\ 1.12\ 0.06
S/temp/C*-180/430*465*-89/58*-82/0*-150 * -170 *-200 *-210 * -220
Quote fizzeksman----------------------------------------------------------------
An analysis will show that planetary magnetic field strength has a direct correspondence to atmospheric density and dynamics. That there is a relationship may be inferred.
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Please note the part about atmospheric density and dynamics.
Quote barakn-----------------------------------------------------------------------
Mercury: No atmosphere, magnetic field
Venus: Dense atmosphere, no magnetic field
Earth: Atmosphere, magnetic field
Mars: Thin atmosphere, magnetic field
Jupiter-Neptune: Dense atmospheres, magnetic fields
Hypothesis nullified by actual data.
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Not so fast barakn breath!
A closer examination will show that faster planetary rotation periods, necessary to sustain strong atmospheric dynamics, coupled with sufficient gravity to retain an atmosphere, increases the probability of stronger magnetic fields associated with those planets. This explanation better accounts for strong magnetic fields of the Jovian planets, Uranus and Neptune. They are believed to have non metallic cores, and the magnetic fields are contemporarily believed to be generated by motion currents of electrically conductive materials such as sea water. Such electrical currents have never been observed in the ocean currents on Earth. The extremely slow rotation (278 days) of Venus, can also account for the current lack of a detectable magnetic field associated with it.
Mercury, as a small planet with insufficient gravity to keep an atmosphere captured, presents an enigma for both the molten core hypothesis, (it is believed to have a solid core by the absence of observable volcanic activity) and the atmospherically driven magnetic field hypothesis. Proposed is that Mercury's proximity to the sun, resulting in high surface temperatures, results in boil off of surface materials sufficient to create a shallow, near surface atmosphere, which results in its very weak magnetic field.
(a good link to reinforce accepted contemporary beliefs)
http://cseligman.com/text/planets/magnetism.htmJack