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From: erkyrath@netcom.com (Andrew Plotkin)
Subject: Re: Directions in space
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Date: Mon, 2 Dec 1996 19:45:13 GMT
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John Hartnup (slim@ladle.demon.co.uk) wrote:
> : The magnetic field of the Earth is not caused by its
> : spin, as far as I'm aware.

> I believe the spin keeps the magnetic field pointing the direction it
> does.

The field is caused by gigantic slow currents in the core of the Earth, 
which are intimately connected with the Earth's spin, if not not "caused 
by" per se.

> Magnetic north is constantly moving (Orienteering maps use magnetic 
> North, and they're out of date within two years)... but it's always
> pretty near true north. Coincidence?

Except when there's a field inversion, after which it's pretty near true 
south. (No, there hasn't been an inversion in recorded history.)

> I await a post from a geographer or physicist.

I ain't one.

--Z

-- 

"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the
borogoves..."
