Earth is two back to back unipolar generators

[sparks]

   Faraday discovered that there is a voltage potential between the outer rim of his spinning disk and the axis.  The below diagram is a picture of earth from one of the poles.  The mass at the poles is moving very slowly compared to the mass at the equators.   This relative angular momentum expresses itself electrically as voltage.  The unipolar currents are generated by the Earth's spin and flow between the poles and the equator at varying intensities dependent on the ability of the mass to conduct them.  The currents keep on flowing from the equator towards the opposite polar region because the disk is reversed in relationship to the cosmic magnetic field permeating the globe.  The magnetic field produced by these currents is then stored in ferrous mass.   The cosmic magnetic field is the propogator of this phenomenon and the currents the effect of the spin of the globe within this polarized magnetic field. 
    Theoretically a conductor could be run between the poles and equator and a pretty massive current then captured at a gap in this conductor.  This conductor would have to be of less resistance than salt water.  Pretty big piece of wire.

[jadaro2600]

This would explain the aurora Borealis...but i don't think that it's two back to back.   More like one, where 'brushes' are caused by the continuous light from the sun and the difference created by it's own shadow and the ionic charge.  The equator is simply the difference between coming and going.

Our moon does very little rotating, yes?  ..I see no aurora on it's poles

I recall the space tether, where a station was able to create massive amount of electric charge across a whip-like structure in space.  There was a recent post on slashdot about the tendencies for plasma to form spindle like structures in space - i assume this is to expedite the dissipation of electricity / charge / heat.  My guess is that the auroras do the same thing.

I think we should take up blasting on the moon and create a solar shield in orbit around the earth...but that's just my proposal to an oil-drunk society at this point.

[Shanti]

Interesting idea!

But you also have to conclude the fact, that the wire which draws the current from the spinning earth is also rotating with the earth!
Strangly Wiki says the mode, when the magnet the conductor and the drawing circuit rotate is undetermined. But actually just some thoughts about that should easily tell, that it will not work...(this is at least my conclusion).
I would argue that very simply. When the drawing conductor also rotates with the earth. The same voltage is induced in the conductor itself, which means, you will not be able to get a circuit, with a potential diference. E.g. the same as if you have a circuit with two batteries and you connect + to + and - to -. No current will flow...
Well you could now state, if the central core of the earth is rotating faster than the crust, then it should be possible to draw a current, but then the current will already flow in the crust...As the crust is then the drawing circuit...

[sparks]

  The conductor will be moving just like the Earth but represents just a short for the potential fields developed between the pole and the equator.  It's current will be an eddy current which would normally cause whatever your prime mover is to load up.  Take awhile to shed all the inertia of the rock? 

[Shanti]

It's current will be an eddy current which would normally cause whatever your prime mover is to load up.

Well I think if your magnet is turning together with the conductor no eddy current will develop.
Otherwise the rotation of every normal magnet (as usually they are also conductors) should immediately incur eddy currents, which would decelerate the magnet...But as far as my personal experience with magnets goes, this doesn't happen...

But I wouldn't bet my hand on that  (these homopolar generators are really tricky...)