How did the earth develop its magnetic field in the first place?

[sphyics]

how did the Earth develop its magnetic field in the first place?
is this the better way to say that Earth has an electromagnetic field or just electric field or magnetic field?

 

[Xnn]

The Earth has 2 magnetic fields. There is one caused from the movement of the molten iron core and another from interaction of the solar wind with the upper atmosphere.

Both are due to electric currents and neither are stable. That is the fields vary over time.

 

[Choragos]

Strictly speaking, we should say it has an electromagnetic field. However, the variation (due to the dynamo) is so slow that it is practically a static magnetic field, with very little electrical component induced.

However, the components of the magnetic field due to ionosphere/solar interactions are of large bandwidth, and are definitely considered electromagnetic.

Nice question