Mysterious Anomaly in Earth's Magnetic Field Is Spreading
New data from the European Space Agency show that a weak spot in the Earth's magnetic field known as the South Atlantic Anomaly has been growing in size since 1970 and may possibly be splitting.
PARIS — A mysterious anomaly in the Earth's magnetic field that stretches from South America to Africa is spreading and scientists do not understand why.
New data from the European Space Agency's SWARM constellation of satellites show that a weak spot in the Earth's magnetic field known as the South Atlantic Anomaly has been growing in size since 1970 and may possibly be developing a second cell centered above the coast of southwest Africa.
The Earth's magnetic field, which is generated by the dynamo action of its molten metal core, protects the planet from the full impact of solar and cosmic radiation. According to the ESA, over the last two centuries, the global magnetic field has lost 9 percent of its strength on a global average.
For now, the most significant effect of the weakening of the South Atlantic Anomaly is interference with satellites and spacecraft that pass over the region. However, the Earth's magnetic field destabilizes and reconstitutes itself over geological time, with sometimes even the north and south magnetic poles trading places.
It is not clear what is causing the weakening of the South Atlantic Anomaly, but it could be related to the African Large Low Shear Velocity Province, one of two giant underground masses of rock that float like hidden continents where the Earth's mantle meets the outer core.
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