Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: More on the North Magnetic Pole (NYT)
    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

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site