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#3b.     Auroral Frequency Map by Hermann Fritz

 (Files in red–history)


2. Magnetic Field

    2H. Oersted, 1820

3. Aurora

   3H. Birkeland 1895

   3a. Loomis & Aurora

   3b. Fritz & Aurora

   3c. The Terrella

4. Electrons

    4H. Thomson, 1896

4a. Electric Fluid
    Hermann Fritz

    Shown here is a map of the frequency with which auroras are seen, produced in 1881 by the German scientist Hermann Fritz (1830-1883). The line of greatest frequency lists 100 auroras per year, while in the center of the pattern auroras are much less frequent.

    Click here for a full size version (232 K) of this image.

    If the Earth's field resembled that of a simple bar magnet ("dipole"), its magnetic pole would be near the northwestern tip of Greenland, in the middle of the pattern. However, the field contains additional complex parts, whose effect does not extend as far into space, and these shift the pole actually observed on the ground to northern Canada, to the location shown on the map.


Last updated 25 November 2001
Re-formatted 3-10-2006

Above is background material for archival reference only.

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