[inquest]

The heat of the solid inner core keeps the molten cocktail of nickel and iron churning in the outer core, which generates a magnetic field.

Something about that doesn't make sense to me. Simply moving a metallic substance around and around shouldn't be able to generate a magnetic field, unless the substance is charged for some reason. But what would be causing it to be charged, and where's the balance of the charge gone to?

[NewHampshireDuo]

It's the proliferation of refrigerator magnets. They have a cumulative effect that is cancelling out the earth's field. ;-)

[SC Swamp Fox]

I would assume that the flowing metal could build up a charge similar to the charges created in the flowing air of a thunderstorm.

I'm not sure a charge is necessary...is there a charge on a bar magnet? There is no current flowing in it, but it has a field.

Once again, I assume that if you allow molten ferrous material to mingle long enough, the atoms will align themselves to each other. Add to that the complex flow patterns resulting from convection and the earth's rotation.....and all bets are off.

[MetalMan]

I think that's just a theory, actually. I've read somewhere that scientists don't know for certain why the magnetic field exists; that's probably the reason they have satellites to study the thing.

At the core of the earth I imagine the pressure is so great that the molten iron is crystalized. Then the molten metal spinning around the crystalized core generates a weak charge.