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Swarm helps explain Earth’s magnetic jerks

01 May 2019

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Our protective magnetic field is always restless, but every now and then something weird happens – it jerks. Although scientists have known about these rapid shifts for some 40 years, the reason why they occur has remained a frustrating mystery, until now.

Since geomagnetic jerks were discovered in 1978 scientists have been trying to work out why the magnetic field suddenly and unexpectedly accelerates.

Looking back at measurement records from the worldwide network of ground-based magnetic observatories, they found that that these jerks, which appear as sharp V-shaped features in graphs of magnetic-field changes, date back as far as 1901, and that the phenomenon occurs about every three to 12 years. Also, they are not consistent across the globe. In 1949, for example, a jerk was measured in North America, but was not detected in Europe.

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