Scientists have long wondered why the polarity of the earth's magnetic field occasionally reverses. Recent studies of our planet's churning interior are offering intriguing clues about how the next reversal may begin
Most of us take it for granted that compasses point north.
Sailors have relied on the earth's magnetic field to navigate for thousands of years. Birds and other magnetically sensitive animals have done so for considerably longer. Strangely enough, however, the planet's magnetic poles have not always been oriented as they are today.
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