NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Feb 5, 09:49 -0800
Tony, you wrote:
"the interesting detail I've learned in the article was that the southern magnetic pole does not reflect all the movements of the northern pole. (I thought it was mirroring it)."
You must have missed my message from three weeks ago.
As a reminder:
Notice also that the south magnetic pole is moving much more slowly. It has been drifting away from the south geographic pole in the period when the north magnetic pole was shooting toward higher northern latitude. These "magnetic poles" are sensitive to very small changes in the actual magnetic field. They represent the locations where the field is exactly vertical. A magnetic needle free to point in any direction in three dimensions would point straight down at the north magnetic pole.
Also notice that the geomagnetic poles (necessarily symmetrical) have been shifting much more slowly. The geomagnetic poles show the location of the poles of the basic dipole representation of the earth's magnetic pole. That is, if you replace the earth's "lumpy" magnetic field by a simple bar magnet most nearly matching the true field, where would its ends be aligned? As you can see in the plot, this "average" pole is moving slowly towards higher geographic latitude. The dipole axis has become more nearly aligned with the rotational axis by about 2.5° in the past century. It's a much slower shift than the motion of the "actual" magnetic poles. There's really no way to guess whether this will continue in the next century.
Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA
