Main Question or Discussion Point
Like the earth, do other planets have magnetism?
Specifically a liquid metal core - which means a minimum size of planet to be big enough to have melted the core and large enough to keep it warm.The current theory is that having a magnetic field around a planet is dependant on having a metal core.
Really that simple? My dynamo experience does not lend me to expect that stirring a bowl of quicksilver should produce any magnetic field. Could you expand on how electrical charge is produced (if the mantle were initially neutral) and maintained (when convection sounds slow compared to the conductivity)?The overall mecahnism is known, conducing iron flows in convection currents creating effecively a dynamo.
Although it clearly isn't size alone that makes this determination (Mercury has a magnetic field and Mars and Venus do not). And yes, it would be fair to say that nobody really knows why. It's amazing how much we don't know. But, regarding the models of magnetic fields of neutron stars; they are only models, and we do have models of planetary magnetic fields. We just can't get the models to match some of the observations.Specifically a liquid metal core - which means a minimum size of planet to be big enough to have melted the core and large enough to keep it warm.
Jupiter has a very strong magnetic field, although it doesn't have any metal.
Under the extreme pressures at the centre of Jupiter, Hydrogen can behave a little like a metal.