July 27 2012 Earth Pole Reversal is Due to Occur

The Earth’s field has alternated between periods of normal polarity, in which the direction of the field was the same as the present direction, and reverse polarity, in which the field was in the opposite direction. These periods are called chrons. The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago. But brief disruptions that do not result in reversal are called geomagnetic excursions.
Motion of the earth’s liquid core, the so-called geodynamo, generates its magnetic field. Gauthier Hulot of the Institut de Physique du Globe de Paris and his colleagues used satellite data recorded 20 years apart to track changes in this field. In two regions of the boundary between the earth’s core and the overlying mantle, the researchers detected a reversed magnetic field. In a section lying beneath the southern tip of Africa, the magnetic field points toward the center of the earth opposite to the dominant outward-pointing field of the Southern Hemisphere. And a second congregation of reversed-flux patches exists near the North Pole. Having modeled the growth and movement of these inverted-flux sections, they can now account for nearly the entire decrease in the main dipole field of the earth over the past 150 years.

Rapid changes in the churning movement of Earth's outer liquid core are weakening the magnetic field in some regions of the planet's surface, according to a June 2008 study. (Credit: Jason Reed/Photodisc/Alamy)

After some 400 years of relative stability, Earth’s North Magnetic Pole has moved nearly 1,100 kilometers out into the Arctic Ocean during the last century and at its present rate could move from northern Canada to Siberia within the next half-century. However, rapid movement of the magnetic pole doesn’t necessarily mean that our planet is going through a large-scale change that would result in the reversal of the Earth’s magnetic field. It may also be part of a normal oscillation. Calculations of the North Magnetic Pole’s location from historical records goes back only about 400 years, while polar observations trace back to John Ross in 1838 at the west coast of Boothia Peninsula.
Some scientists point that the Northern Lights, which are triggered by the sun and fixed in position by the magnetic field, drift with the movement of the North Magnetic Pole and may soon be visible in more southerly parts of Siberia and Europe – and less so in northern Canada and Alaska.

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