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Researchers believe the earth’s inner core has stopped spinning and could now be turning in reverse.
According to scientists Yi Yang and Xiaodong Song from Peking University in China, the earth’s inner core has nearly ceased rotation in the recent decade and may even be ‘experiencing a turning-back in a multidecadal oscillation, with another turning point in the early 1970s’.
The paper, published in Nature Geoscience, looks at the earth’s mysterious innards by observing seismic waves from earthquakes that blasted through the core.
Their data of the inner core’s seismic waves go as far back as the Alaskan records, which begin in the 1960s.
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They’ve suggested these changes are part of an ‘oscillation’ cycle, likely to last seven decades.
Xiaodong Song, a seismologist at Peking University and an author of the study, described the inner core as ‘a planet within a planet, so how it moves is obviously very important’.
However, how it works largely remains a mystery.
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So far, we know it’s made out of primarily solid iron and, according to National Geographic, it has a radius of 758 miles (1,220 km) and a temperature of around 9,392° F (5,200° C).
That’s one spicy meatball.
“There are two major forces acting on the inner core,” Yang and Song said in an email to Vice.
They said the first is the electromagnetic force. The earth’s magnetic field, which protects the planet from cosmic radiation, is created by fluid motion from the outer core.
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The magnetic field acting on the metallic inner core is expected to drive the inner core to rotate by ‘electromagnetic coupling’.
They continued: “The other is gravity force. The mantle and inner core are both highly heterogeneous, so the gravity between their structures tends to drag the inner core to the position of gravitational equilibrium, so called gravitational coupling.”
However, this ‘tug and war’ causes the inner core to spin back and forth for roughly a ‘70-year oscillation’.
The scientists added that their research supports the inner rotation and, furthermore, ‘the multidecadal pattern of the rotation’.
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John Vidale, a seismologist at the University of Southern California who was not involved in the study, said there’s so much conflicting research surrounding the inner core rotation.
And while its inaccessibility makes it difficult to confirm, he remains hopeful.
“It’s certainly possible we’ll never figure it out,” he told The New York Times. “I’m an optimist. The pieces are going to fall into place someday.”