Earth’s core might be reversing its spin. It ‘won’t affect our daily lives,’ expert says

Sergei Korsakov/AP

Brendan Rascius
Mon, January 23, 2023 

Earth’s inner core, a red-hot ball of iron 1,800 miles below our feet, stopped spinning recently, and it may now be reversing directions, according to an analysis of seismic activity.

The discovery indicates that the Earth’s center regularly pauses and reverses its rotation, researchers in China wrote in a study published Jan. 23 in the journal Nature Geoscience.

“We show surprising observations that indicate the inner core has nearly ceased its rotation in the recent decade and may be experiencing a turning back in a multidecadal oscillation, with another turning point in the early 1970s,” Dr. Yi Yang and Dr. Xiaodong Song, scientists at Peking University, wrote in the study.

Just as the Earth spins, the planet’s inner core turns, though not necessarily at the same speed, and some research indicates the core moves faster, according to the National Science Foundation. The inner core can spin independently because it is encased in a liquid outer core, similar to an egg yolk inside the more fluid egg white.


By analyzing earthquake data from across the globe over the last 28 years, researchers confirmed that the inner core’s rotation relative to the Earth’s mantle — the bulk of the planet’s interior between the core and the outer crust — had ceased around 2009, according to a story about the study in Nature Geoscience.

Additionally, their findings suggests the inner core may be in the process of reversing the direction of its spin, leading researchers to hypothesize a pattern.

“We infer the inner core rotation changes direction every 35 years,” Dr. Song told McClatchy News.

Why exactly this phenomenon occurs is not clear to researchers. The gravitational and magnetic forces that factor into the inner core’s movement are likely partly responsible, they said.

Importantly, their findings also imply a strong connection between the crust, the thin surface slice that we inhabit, and the deepest parts of the globe, researchers said.

The core’s multi-decade rotational pattern “coincides with several important geophysical observations,” researchers wrote, including changes in the magnetic field and the length of the day, meaning the inner workings of the planet could impact the duration of our days.

Still, we have no reason to be concerned, as these changes will not be noticeable to us, researchers said.

“The phenomenon does not affect our daily lives,” Dr. Song said.

Though more research is needed, these results represent another step in the process of unraveling the complex mechanisms of the inner Earth, an untraversable inferno that remains very difficult to study.

Earth's inner core may have started spinning other way: study

Daniel Lawler
Mon, January 23, 2023 


Far below our feet, a giant may have started moving against us.

Earth's inner core, a hot iron ball the size of Pluto, has stopped spinning in the same direction as the rest of the planet and might even be rotating the other way, research suggested on Monday.

Roughly 5,000 kilometres (3,100 miles) below the surface we live on, this "planet within the planet" can spin independently because it floats in the liquid metal outer core.

Exactly how the inner core rotates has been a matter of debate between scientists -- and the latest research is expected to prove controversial.

What little is known about the inner core comes from measuring the tiny differences in seismic waves -- created by earthquakes or sometimes nuclear explosions -- as they pass through the middle of the Earth.

Seeking to track the inner core's movements, new research published in the journal Nature Geoscience analysed seismic waves from repeating earthquakes over the last six decades.

The study's authors, Xiaodong Song and Yi Yang of China's Peking University, said they found that the inner core's rotation "came to near halt around 2009 and then turned in an opposite direction".

"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", meaning it changes direction roughly every 35 years, they added.

They said it previously changed direction in the early 1970s, and predicted the next about-face would be in the mid-2040s.

The researchers said this rotation roughly lines up with changes in what is called the "length of day" -- small variations in the exact time it takes Earth to rotate on its axis.

- Stuck in the middle -

So far there is little to indicate that what the inner core does has much effect on surface dwellers.

But the researchers said they believed there were physical links between all Earth's layers, from the inner core to the surface.

"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.

Experts not involved in the study expressed caution about its findings, pointing to several other theories and warning that many mysteries remain about the centre of the Earth.

"This is a very careful study by excellent scientists putting in a lot of data," said John Vidale, a seismologist at the University of Southern California.

"(But) none of the models explain all the data very well in my opinion," he added.

Vidale published research last year suggesting that the inner core oscillates far more quickly, changing direction every six years or so. His work was based on seismic waves from two nuclear explosions in the late 1960s and early 1970s.

That timeframe is around the point when Monday's research says the inner core last changed direction -- which Vidale called "kind of a coincidence".

- Geophysicists 'divided' -

Another theory -- which Vidale said has some good evidence supporting it -- is that the inner core only moved significantly between 2001 to 2013 and has stayed put since.

Hrvoje Tkalcic, a geophysicist at the Australian National University, has published research suggesting that the inner core's cycle is every 20 to 30 years, rather than the 70 proposed in the latest study.

"These mathematical models are most likely all incorrect because they explain the observed data but are not required by the data," Tkalcic said.

"Therefore, the geophysical community will be divided about this finding and the topic will remain controversial."

He compared seismologists to doctors "who study the internal organs of patients' bodies using imperfect or limited equipment".

Lacking something like a CT scan, "our image of the inner Earth is still blurry", he said, predicting more surprises ahead.

That could include more about a theory that the inner core might have yet another iron ball inside it -- like a Russian doll.

"Something's happening and I think we're gonna figure it out," Vidale said.

"But it may take a decade."

dl/gil

The mysterious iron ball at the center of the Earth may have stopped spinning and reversed direction


Chris Panella,Morgan McFall-Johnsen
Tue, January 24, 2023 

A 3D rendering of the Earth's layers, including its inner core.Getty Images

Earth's inner core may have paused and reversed its spin, a new study suggests.

Earthquakes and nuclear blasts can send seismic waves through the mysterious solid-iron core.

Those waves hint that the core changed direction in the 1970s, and may be undergoing another reversal today.

Living on Earth's surface, we only see about 0.5% of the planet. Deep below the crust, then the hot rock mantle, then the liquified outer core, lies one of our planet's biggest mysteries: the solid iron core at the center.

That iron ball — Earth's inner core — may have recently stopped rotating, then reversed direction for no apparent reason, a new study found.

That may sound apocalyptic, but don't worry. Scientists don't think it will significantly change life on the surface, except by befuddling them.

"It's probably benign, but we don't want to have things we don't understand deep in the Earth," John Vidale, a geophysicist at the University of Southern California, told The Washington Post.

Published in the journal Nature Geoscience on Monday, the peer-reviewed research suggests that the solid inner core of the Earth could experience changes in its rotation every several decades.

Clues from earthquakes and nuclear blasts hint at a change around 2009

The light from an atomic bomb test explosion is reflected in the waters of Enewetak Atoll on May 30, 1956.STR New / Reuters

Scientists can't look directly at the inner core, but they can get hints of its activities from powerful earthquakes and Cold War nuclear-weapons tests, which have sent seismic waves reverberating through the center of the Earth.

Those deep seismic waves have shown that the core is mostly composed of pure, solid iron and nickel, and that it may spin a little faster than the rest of the Earth.

If the inner core was inert, spinning in line with the outer layers of the planet, similar waves should travel similar paths through it. But over time, the movement of those waves changes, indicating that the core itself is changing. Spinning is one of the leading explanations for these seismic mismatches.

The new study throws a wrench in the core's spin. It looks closely at seismic waves from the 1960s to the present day. The researchers found a quirk starting in 2009: In the last decade, the paths of similar seismic waves did not change. That suggests the inner core may have stopped spinning around that time.

Data from two pairs of nuclear blasts hint at a similar pause around 1971, with the core spinning eastward afterwards, leading the researchers to believe that the inner core may pause and reverse its spin about every 70 years.

The theory is that Earth's magnetic field pulls the inner core and causes it to spin, while the gravitational field of the mantle creates a counter force, dragging on the inner core. Every few decades, one force may win out over the other, changing the spin of the great iron ball.

The inner core is a major mystery, and we may never solve it

An artist's conception of the different layer's of our planet, including the crust, mantle, and inner and outer cores.Getty

Explaining these quirks in the seismic record is difficult, and involves speculation, since there is so little information about the inner core.

Another explanation is that the surface of the inner core is changing over time, rather than the whole iron ball spinning. Lianxing Wen, a seismologist at Stony Brook University, discussed this theory in a 2006 paper and still stands by it today. He told The Washington Post that would explain the pauses in 1971 and 2009.

"This study misinterprets the seismic signals that are caused by episodic changes of the Earth's inner core surface," Wen told the Post.

The new study may help shed further light on the mysterious nature of the inner core and how it interacts with Earth's other layers. It could be a long time before scientists piece together the full picture, though — if they ever do.

"It's certainly possible we'll never figure it out," Vidale told The New York Times.

An illustration of Earth's core.Getty

Still, he said, "I'm an optimist. The pieces are going to fall into place someday."

Until then, Vidale and his colleagues will just keep listening to seismic waves that travel from one side of the planet to the other, straight through the iron core that the