Does the Earths own magnetic field ever reverse?
Note: This subject is extensively discussed in Magnetic Reversals and Moving Continents, part of an extensive web-collection “The Great Magnet, the Earth” whose home page is here. Yes, it apparently does, but at very infrequent intervals. That magnetic field is caused by electric currents in the Earth’s molten core, and is observed to change slowly from year to year. On rare occasions, however, the dominant pattern of currents seems to reverse direction.
