<<A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged. The Earth's field has alternated between periods of normal polarity, in which the predominant direction of the field was the same as the present direction, and reverse polarity, in which it was the opposite. These periods are called chrons.
Reversal occurrences are statistically random, with some periods lasting as little as 200 years. There have been 183 reversals over the last 83 million years. The latest, the Brunhes–Matuyama reversal, occurred 780,000 years ago, and may have happened very quickly, within a human lifetime. A brief complete reversal, known as the Laschamp event, occurred only 41,000 years ago during the last glacial period. That reversal lasted only about 440 years with the actual change of polarity lasting around 250 years. During this change the strength of the magnetic field weakened to 5% of its present strength. Brief disruptions that do not result in reversal are called geomagnetic excursions.>>
<<The first expedition to reach the North Magnetic Pole was led by James Clark Ross, who found it at Cape Adelaide on the Boothia Peninsula on June 1, 1831. Roald Amundsen found the North Magnetic Pole in a slightly different location in 1903. The third observation was by Canadian government scientists Paul Serson and Jack Clark, of the Dominion Astrophysical Observatory, who found the pole at Allen Lake on Prince of Wales Island in 1947.
The Canadian government has made several measurements since, which show that the North Magnetic Pole is moving continually northwestward. In 2001, an expedition located the pole at 81.3°N 110.8°W. In 2007, the latest survey found the pole at 83.95°N 120.72°W. During the 20th century it moved 1100 km, and since 1970 its rate of motion has accelerated from 9 km/year to approximately 52 km/year (2001–2007 average). Members of the 2007 expedition to locate the magnetic north pole wrote that such expeditions have become logistically difficult, as the pole moves farther away from inhabited locations. They expect that in the future, the magnetic pole position will be obtained from satellite data instead of ground surveys.
This general movement is in addition to a daily or diurnal variation in which the North Magnetic Pole describes a rough ellipse, with a maximum deviation of 80 km from its mean position. This effect is due to disturbances of the geomagnetic field by charged particles from the Sun.>>
This must drive folks with strong magnetoreception to distraction. As the Earth cools (title of my favorite soap opera) the 1/2 Gauss field weakens. Before we get exterminated by the solar wind, could we set up a series of geostationary satellites to create a 0.1 Gauss electromagnetic field to supplement the geomagnetic field? Such an array of current loops could surround Mars to restore protection from the solar wind and help with terraforming. NASA is floating a scheme of putting a huge electromagnet at Mars L1 Lagrange point, putting the red planet in a magnetotail, so generating a half-Gauss field with a satellite is feasible. We already have valuable satellites at Earth L1 (e.g. SOHO) thus eliminating a similar Earth-enveloping magnetotail; a geostationary array presents itself.