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Earth Magnetic Field Distribution

April 9th Fact-of-the-Day

Earth's geomagnetic field is rather weak at and above the surface of the earth, but complexly-structured magnetic fields inside earth's core that produce it are thought to be about 100 times stronger. The weaker field at surface is called a magnetic dipole, because it has two poles. That dipole produces an external magnetic field around the earth that is generally similar in shape to the field surrounding a bar magnet. However, satellite field-strength measurements show that earth's dipole field is not distributed evenly like a bar magnet field and that most of the field strength originates below Antarctica, Siberia, and North America. Furthermore, comparisons of magnetic field-strength maps made from accurate measurements taken 20-years apart show significant changes in field distribution. ©2005 Martek International All rights reserved.


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