Aspects of this topic are discussed in the following places at Britannica.
...a magnet aligned with the planet’s rotation axis. The figure shows such a field for a bar magnet located at the centre of a sphere. If the sphere is taken to be the Earth with the north geographic pole at the top, the magnet must be oriented with its north magnetic pole downward toward the south geographic pole. Then, magnetic field lines leave the north pole of the magnet and curve around...
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