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Steady On

September 4, 2018

Earth’s magnetic field is constantly changing. Right now, for example, the magnetic north pole is moving about 40 miles per year. And the strength of the magnetic field has dropped over the last couple of centuries. That’s led to speculation that the field is about to make the biggest change of all: a complete reversal, with the north magnetic pole becoming the south pole and vice versa. But a recent study says that might not be the case.

Earth’s magnetic field is generated deep in its core. Our planet has a solid iron core that’s surrounded by a layer of molten metal. The solid and liquid cores rotate at different speeds. That creates electric currents, which in turn produce a magnetic field. The field flips probably are caused by changes in the core, although scientists don’t yet know how this works.

Over the past 20 million years, the field has flipped an average of about once every 250,000 years. But the last reversal took place 780,000 years ago. And there’s a spot over the South Atlantic where the field is quite weak. That’s fed the idea that the field is about to reverse.

But the recent study looked at the state of the magnetic field at several times over the last 50,000 years or so. It found several eras when the field looked almost exactly like it does today. None of those eras led to a permanent switch. So the researchers say that despite the fluctuations, the field probably isn’t due for a reversal any time soon.

Script by Damond Benningfield

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