Earth's magnetic polarity reversals
Name: glen a musgrave
I understand that the Earth's polarity changed
several times in the past (reversed directions).
Are there any theories as to why that occured?
This is an easy one to
Nobody knows why the
polarity of the Earth's magnetic field changes.
As you might imagine, however, many scientists are working
on this problem.
Some recent investigations have examined how the magnetic
field approaches a polarity reversal. Since the magnetic
field of the earth is locked into rocks when the rocks
first form, it is possible to study how the magnetic
field of the earth changes by studying the magnetic field
of the rocks. These studies indicate that the strength of
the magnetic field follows a fairly systematic pattern
of strengthening, then weakening. When the field becomes
very weak, it may reverse direction. Whether the field
reverses itself or not, the field
rapidly reenergizes after it gets to a weak point.
By making observations such as these, it should be possible
to eventually determine why the magnetic field reverses.
Right now, though, it's something of a mystery.
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Update: June 2012