July 13, 2004 | David F. Coppedge

Is Earth’s Magnetic Field Reversing?

The New York Times and World Net Daily have stories about Earth’s magnetic field.  The strength of the field has declined 10-15% over the past 150 years.  If undergoing a reversal, which some physicists say is overdue, it could have profound effects on migratory animals like birds and turtles, and allow more dangerous radiation to hit the Earth’s surface.  New satellites are trying to get better measurements of the collapse of the field.  During a reversal, the field strength drops to zero, then rebounds in the other direction, such that compass needles would point south.

The important thing in these stories is not the long-age claims, which are not subject to calibration without long-age assumptions, but the fact that an objectively measured physical parameter shows a steep and steady decline over 150 years.  This challenges the belief that it has been around for billions of years (see 03/04/2003 headline).
    Scientists do not understand how planets generate magnetic fields.  Why is Earth the only rocky planet with a strong field?  Why are those of Uranus and Neptune so erratic?  Saturn explodes the most popular dynamo models by possessing a strong field without an angle between the rotation axis and the magnetic field axis (the divergence is only 0.2%).  The new measurements of Saturn’s magnetosphere by the Cassini spacecraft should prove interesting.
    Another important thing to know is that life depends on the protective bubble provided by Earth’s magnetic field (see 05/10/2002 headline).  Better hope the collapse doesn’t occur during your beach vacation.

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Categories: Physical Science, Physics

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