Earth's Magnetism

This idea remains part of currents grand unification theories that are attempting to bring together the electromagnetic and nuclear forces that, with gravitation, underlie the interactions of all matter. The earth’s poles switch because the earth spins on an axis and slowly flips. No interpretation, however, has thus far been confirmed. All known magnetic particles are dipole in nature - that is, they contain both a “north” and “south” magnetic pole - but the possible existence of magnetic monopoles was proposed by symmetry theories in the 1930’s. Variations in the magnetic field of the earth include secular variation - the change in the direction of the field caused by shifting of the poles.

The magnetic poles do not correspond with the geographic poles of its axis, and the position of the magnetic poles is not constant and shows an appreciable change from year to year.

There is also the theoretical elementary particle containing only one magnetic pole, it is called a monopole. Methods for detecting monopoles have been devised, and events recorded in the early 1980’s have been interpreted by some researchers as suggestions to their existence. A smaller annual variation also exists, as does diurnal, or daily, which can only be detected by sensitive instruments. And so, the only way, as far as we know, to switch the poles of a magnet, is to turn the magnet upside-down. Although the conductivity of the air near the earth is small, air is not a perfect insulator, and the negative charge would drain off quickly if it were not being continuously replenished in some way. This is a periodic variation that repeats itself after 960 years.

Measurements of the secular variation show that the entire magnetic field has a tendency to drift westward at the rate of 12 - 15 miles per year.