Earth's Core Spinning in Opposite Direction May Lead to Slightly Shorter Days, Scientists Found

Research published in the journal Nature Geoscience said Earth's core nearly stopped rotating around 2009, before turning in the opposite direction

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Earth's core may have slowed its rotation before completely switching directions around more than a decade ago, scientists suggested in a new study.

In a report published in Nature Geoscience this week, seismologists Xiaodong Song and Yi Yang of Peking University in China said that the Earth's iron core slowed its rotation in 2009. It briefly fell in sync with the planet's overall rotation during this time.

Then, the seismologists say, the core "turned in an opposite direction," per CBS News.

"We believe the inner core rotates, relative to the Earth's surface, back and forth, like a swing," they told AFP.

"One cycle of the swing is about seven decades," the team explained, meaning that the core would switch direction about every 35 years.

The change in the rotation would shorten the length of the day by a fraction of a millisecond over 12 months, the study suggested, as noted by the Wall Street Journal.

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Earth's core is surrounded by a fluid outer core of molten iron and nickel that is 1,500 miles thick. It is located roughly 3,100 miles below the surface and is believed to produce the magnetic field surrounding the planet.

The researchers estimated that the core also changed directions sometime in the 1970s and could switch again in the 2040s, AFP reported.

They also believe all of Earth's layers are physically linked to each other.

"We hope our study can motivate some researchers to build and test models which treat the whole Earth as an integrated dynamic system," they said, according to CBS News.

During their study, the team analyzed seismic waves from earthquakes over the last six decades, per Phys.org.

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John Vidale, a University of Southern California seismologist, told AFP that there's doubt around the team's findings. He explained that other research suggests the inner core changes direction every six years.

"This is a very careful study by excellent scientists putting in a lot of data," he told the outlet. "None of the models explain all the data very well, in my opinion."

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