The inner core of our planet has started spinning slower and slower, new research has revealed
Compared to the speed of the Earth's surface, the inner core was previously thought to rotate faster. However, since 2010, it has begun to slow down, according to a new paper in the journal Nature.
Now, our inner core is spinning slower than the surface for the first time in decades, and this might lead to changes in the length of our days.
"When I first saw the seismograms that hinted at this change, I was stumped," John Vidale, a professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences, said in a statement.
"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."
The Earth is composed of several layers, broadly classified into the crust, mantle, outer core, and inner core, each with distinct characteristics and compositions.
The crust is the Earth's outermost layer, and varies in thickness from between 3 and 44 miles. Beneath the crust is the mantle, which extends to about 1,800 miles deep, and is made mostly of silicate minerals rich in iron and magnesium. The outer core lies beneath the mantle and extends from about 1,800 miles to 3,200 miles deep, and is mainly made up of liquid iron and nickel—the movement of which generates the Earth's magnetic field.
The inner core is the Earth's innermost layer, with a radius of about 760 miles—about the same size as the moon—and is a solid ball of iron and nickel at the center of our planet.
Due to its immense depth within the Earth, scientists must rely on the seismic waves of earthquakes to study the movement of the inner core. In the paper, the researchers describe how they analyzed seismic data from 121 repeating earthquakes between 1991 and 2023 near the South Sandwich Islands in the South Atlantic Ocean, as well as data from various nuclear tests.
They found that the inner core was slowing down its rotation as a result of the churning of the liquid in the outer core, combined with gravitational pulling from the mantle.
This may result in slight changes to the length of a day, but by only fractions of a second.
"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."
The researchers hope to further drill down into why the core is slowing, and what kind of effects it will have on our planet.
"The dance of the inner core might be even more lively than we know so far," Vidale said.
Do you have a tip on a science story that Newsweek should be covering? Do you have a question about the Earth's core? Let us know via science@newsweek.com.
Disclaimer: The copyright of this article belongs to the original author. Reposting this article is solely for the purpose of information dissemination and does not constitute any investment advice. If there is any infringement, please contact us immediately. We will make corrections or deletions as necessary. Thank you.
