Magnetic Fields of Planets

Current understanding of planetary magnetic fields is that they are the products of what is loosely termed dynamo currents.

In the case of our own planet, the source of the magnetic field appears to be deep below the crust. However, currents in the ionosphere, high above our planets are also known to contribute.

The exact nature of the below ground current is unknown, but it is tempting to suppose that it is a plasma current, just like the one in the ionosphere. This is especially true for those who prescribe to the idea that planets may be hollow.

The fact that Earth's magnetic poles are erratic, sometimes deviating as much as 80 km from their average position, strongly indicates that their source are highly fluid.

The fact that Earth's south pole and north pole rarely position themselves at exact opposites to each other indicate that there is not in fact a single magnetic field. There is a field to the north and a field to the south that are loosely connected through magnetism. Together, they produce an overall magnetic field, and the appearance of being from a single source.

In actual fact, there is four major contributors to the overall field. There is an internal and external current producing the magnetic north pole, and a similar duo to the south, producing the south magnetic pole.

Plasma currents at the poles producing an overall magnetic field

There is no direct physical contact between the currents. They act together purely through magnetic interaction. This is evident on Jupiter which have magnetic poles that act fairly independently of each other.

Further evidence to support this view can be found on Uranus, which has at times more than two magnetic fields. It appears that the external and the internal plasma currents of Uranus are out of tune with each other, sometimes lining up and sometimes not.