The Earth’s core may have slowed its rotation before it completely reversed direction more than a decade ago, scientists have suggested in a new study.
In a report published in Nature Earth science This week, seismologists Xiaodong Song and Yi Yang of Beijing University in China found that Earth’s iron core slowed its rotation in 2009. It briefly synchronized with the general rotation of the planet at that time.
Then, seismologists said, the core “rotated in the opposite direction” according to CBS News.
“We believe the inner core rotates back and forth relative to the Earth’s surface, like a seesaw,” they told AFP.
“One fluctuating cycle lasts about seven decades,” the team explained, meaning the core changes direction roughly every 35 years.
Changing the rotation would shorten day length by a fraction of a millisecond over 12 months, the study suggests. Wall Street Journal.
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The Earth’s core is surrounded by a liquid outer core of molten iron and nickel 1,500 miles thick. It lies about 3,100 miles below the surface and is thought to produce the magnetic field surrounding the planet.
Scientists have estimated that the core also changed direction in the 1970s and may change direction again in the 2040s.
They also believe that all layers of the Earth are physically connected to each other.
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“We hope our study can motivate some researchers to build and test models that treat the entire Earth as an integrated dynamic system,” they said, according to CBS News.
During their research, the team analyzed seismic waves from earthquakes over the past six decades, according to Phys.org.
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John Vidale, a seismologist at the University of Southern California, told AFP there were doubts about the team’s findings. He explained that other studies suggest that the inner core changes direction every six years.
“It’s a very careful study done by great scientists who have entered a lot of data,” he told the outlet. “In my opinion, none of the models explains all the data very well.”