Earth and the Moon

The Magnetic Field

Does Earth’s magnetic field ever change?

Yes, the magnetic field is constantly changing, though very slowly. The magnetic poles actually drift several kilometers each year, often in seemingly random directions. Over thousands of years, the strength of the magnetic field can go up and down significantly. Even more amazing, Earth’s magnetic field can reverse directions—the north magnetic pole becomes the south magnetic pole, and vice versa. According to scientific measurements, our planet’s magnetic field last had a polarity reversal about 800,000 years ago.


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