New Delhi, India

The latest study has confirmed that the Earth’s inner core is slowing down in relation to the surface of the planet. The decrease in speed started over 10 years ago - around 2010. This apparently happened for the first time since scientists developed the capacity to measure it. 

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The inner core is solid and made up of iron and nickel. It is a very hot and dense centre of our planet, with temperatures up to 5,500 degrees Celsius. The liquid iron-nickel outer core surrounds a solid iron-nickel spherical within it. The inner core is roughly the size of the moon and rests more than 3,000 miles beneath our feet. 

Researchers can't visit or view it but they can study it using the seismic waves of earthquakes. 

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Scientists at the University of Southern California have proven that the Earth's inner core is backtracking, meaning slowing down. The study, titled, "Inner core backtracking by seismic waveform change reversals", was published in Nature on Wednesday (Jun 12). 

"The pattern of matches, together with previous studies, demonstrates that the inner core gradually super-rotated from 2003 to 2008, and then from 2008 to 2023 sub-rotated two to three times more slowly back through the same path," the researchers said. 

John Vidale, Dean's Professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences, said as quoted by the official site: "When I first saw the seismograms that hinted at this change, I was stumped." 

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"But when we found two dozen more observations signaling the same pattern, the result was inescapable. The inner core had slowed down for the first time in many decades. Other scientists have recently argued for similar and different models, but our latest study provides the most convincing resolution," Vidale added. 

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The official release mentioned that the inner core is considered to be reversing and backtracking relative to the planet's surface as a result of moving somewhat slower than the Earth's mantle for the first time in about 40 years. 

This could eventually alter the entire planet's rotation, prolonging our days, but if there are any noticeable consequences, they will most likely be on the geomagnetic field. 

Vidale also said that the backtracking of the inner core may alter the length of a day by fractions of a second. As quoted, he said, "It's very hard to notice, on the order of a thousandth of a second, almost lost in the noise of the churning oceans and atmosphere." 

(With inputs from agencies)