Science

Jim__

(14,347 posts) Wed Jun 12, 2024, 04:43 PM Jun 2024

Study confirms the rotation of Earth's inner core has slowed

The inner core began to decrease its speed around 2010, moving slower than the Earth’s surface. Credit: University of Southern California
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University of Southern California scientists have proven that the Earth's inner core is backtracking—slowing down—in relation to the planet's surface, as shown in new research published in Nature.

Movement of the inner core has been debated by the scientific community for two decades, with some research indicating that the inner core rotates faster than the planet's surface. The new USC study provides unambiguous evidence that the inner core began to decrease its speed around 2010, moving slower than the Earth's surface.

"When I first saw the seismograms that hinted at this change, I was stumped," said John Vidale, Dean's Professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences. "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 inner core is a solid iron-nickel sphere surrounded by the liquid iron-nickel outer core. Roughly the size of the moon, the inner core sits more than 3,000 miles under our feet and presents a challenge to researchers: It can't be visited or viewed. Scientists must use the seismic waves of earthquakes to create renderings of the inner core's movement.

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8 replies

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Study confirms the rotation of Earth's inner core has slowed (Original Post) Jim__ Jun 2024 OP

So interesting. flying_wahini Jun 2024 #1

I went thru the article, slightlv Jun 2024 #2

The abstract to the paper does say that this influences the earth's magnetic field. Jim__ Jun 2024 #5

I have some questions about this for our resident scientists... JoseBalow Jun 2024 #3

1. lose magnetosphere -- yes localroger Jun 2024 #4

This is so interesting JoseBalow Jun 2024 #6

She is exhausted. Lulu KC Jun 2024 #7

Oh, no! This means DavidDvorkin Jun 2024 #8

flying_wahini

(7,694 posts)

1. So interesting.

Reply to Jim__ (Original post)

Wed Jun 12, 2024, 04:52 PM

Jun 2024

In my head I just wrote a movie about the Earth slowing down, the long and longer seasons and
in the end scene people and everything just floats away into the sky.

slightlv

(3,701 posts)

2. I went thru the article,

Reply to Jim__ (Original post)

Wed Jun 12, 2024, 04:53 PM

Jun 2024

but I still have a question... would this slowing down have any affect on our magnetosphere? Would it put us at risk for greater danger during these solar eruptions? On one hand it feels like it would, but the article just kind of glosses over that, instead concentrating on the minor change in the length of the day.

Jim__

(14,347 posts)

5. The abstract to the paper does say that this influences the earth's magnetic field.

Reply to slightlv (Reply #2)

Wed Jun 12, 2024, 06:45 PM

Jun 2024

From the abstract of the paper.

The solid inner core, suspended within the liquid outer core and anchored by gravity, has been inferred to rotate relative to the surface of Earth or change over years to decades based on changes in seismograms from repeating earthquakes and explosions1,2. It has a rich inner structure3,4,5,6 and influences the pattern of outer core convection and therefore Earth’s magnetic field.

...

The matching waveforms reveal times at which the inner core re-occupies the same position, relative to the mantle, as it did at some time in the past. 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. These matches enable precise and unambiguous tracking of inner core progression and regression. The resolved different rates of forward and backward motion suggest that new models will be necessary for the dynamics between the inner core, outer core and mantle.

They don't know the full implications of these changes to the rotation rate of the core. This is something they want to study to gain a better understanding.

JoseBalow

(4,384 posts)

3. I have some questions about this for our resident scientists...

Reply to Jim__ (Original post)

Wed Jun 12, 2024, 05:14 PM

Jun 2024

If the Earth's core were to stop rotating, wouldn't we lose the magnetosphere?

And if that happened, wouldn't the sun blow away our atmosphere, like on Mars?

Is it possible to calculate or predict how much slowing would be required to render the magnetosphere too weak to protect us from solar particles?

I'm also wondering, what would kill all life on Earth first, the above scenario, or our sun's expansion/supernova?

Is there enough data yet to extrapolate the rate of slowing to predict when core rotation might stop altogether, or slow it enough to render the magnetosphere too weak to protect Earth from the sun?

These topics fascinate me, I wish I knew more about it.

localroger

(3,688 posts)

4. 1. lose magnetosphere -- yes

Reply to JoseBalow (Reply #3)

Wed Jun 12, 2024, 06:38 PM

Jun 2024

2. atmosphere blow away -- yes, but it would take hundreds of millions of years, like on Mars.
3. magnetosphere too weak -- effect on life is not that big. Most particles would still be stopped by atmosphere. Energy events (solar flares, etc.) would be a bigger problem than they are, but mostly not lethal to life.
4. Kill all life first -- sun going nova. Partly because slowless of losing atmosphere, partly because...
5. Rate of slowing to core stop -- never. There is some momentum exchange between the layers and changes can have dramatic effects like magnetic pole reversals but the Earth has a LOT of angular momentum and it has to go somewhere. Quite a lot of it goes toward slowing down the Moon via tides. (Sun will go nova before Earth and Moon tidally lock, though. LONG before.)

JoseBalow

(4,384 posts)

6. This is so interesting

Reply to localroger (Reply #4)

Wed Jun 12, 2024, 08:19 PM

Jun 2024

Thank you!

Lulu KC

(3,024 posts)

7. She is exhausted.

Reply to Jim__ (Original post)

Wed Jun 12, 2024, 09:23 PM

Jun 2024

I might be projecting.

DavidDvorkin

(19,756 posts)

8. Oh, no! This means

Reply to Jim__ (Original post)

Wed Jun 12, 2024, 10:48 PM

Jun 2024

that we'll have to send people into the earth in a special vehicle with a great big drill in front so that they can travel to the core and explode a huge nuclear bomb to speed it up again as they fight their way back to the surface despite technical failures and human treachery while a romance blossoms between the one handsome male and the one beautiful female member of the crew!

I hope there's high quality video.

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