How the Earth’s Magnetic Field is Changing

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The earth’s magnetic field protects our world from bombarding cosmic radiation and charge particles from outer space.  The field itself is in flux, constantly changing.  In November of 2013, the European Space Agency launched the three satellite constellation known as Swarm.

Changes in the Earth’s Magnetic Field

The ESA recently released the results of data collection from Swarm from the past six months. The measurements collected about the earth’s magnetic field show a trend towards weakening of the field, with the western hemisphere showing the greatest decline.  Not all areas of the earth are weakening.  The data measurements show that other areas of the earth, such as a section over the Indian Ocean are strengthening.

The data collected by Swarm also confirmed the continued trend of the Magnetic North Pole moving towards Siberia.

‘Snapshot’ of the main magnetic field at Earth’s surface as of June 2014 based on Swarm data. The measurements are dominated by the magnetic contribution from Earth’s core (about 95%) while the contributions from other sources (the mantle, crust, oceans, ionosphere and magnetosphere) make up the rest. Red represents areas where the magnetic field is stronger, while blues show areas where it is weaker. Source: ESA/DTU Space
A view of the main magnetic field at Earth’s surface as of June 2014 based on Swarm data. The measurements are dominated by the magnetic contribution from Earth’s core (about 95%) while the contributions from other sources (the mantle, crust, oceans, ionosphere and magnetosphere) make up the rest. Red represents areas where the magnetic field is stronger, while blues show areas where it is weaker. Source: ESA/DTU Space

Changing Polarity of the Earth

Examining the geologic record can provide evidence of magnetic polarity reversals. Lavas and sediments often retain a record of the ambient magnetic field at the time of deposition when they harden.

The geomagnetic poles are currently roughly aligned with the geographic poles, although the magnetic poles periodically deviate from their optimal state and “excursion” away from the geographic poles. The shifting polarity can eventually result in the poles flipping with the South Pole where the North Pole is and vice versa.

How Often Does Pole Reversal Happen?

Reversals do not happen overnight; they take hundreds to thousands of years to occur.

These reversals appear to happen at random, with no discernible pattern. They can occur as regularly as once every 10,000 years or as infrequently as once every 50 million years or more. The latest reversal occurred approximately 780,000 years ago.

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