Earth's Core Has Slowed So Much It's Moving Backward, Scientists Confirm (cnn.com) 48
An anonymous reader quotes a report from CNN: Deep inside Earth is a solid metal ball that rotates independently of our spinning planet, like a top whirling around inside a bigger top, shrouded in mystery. This inner core has intrigued researchers since its discovery by Danish seismologist Inge Lehmann in 1936, and how it moves -- its rotation speed and direction -- has been at the center of a decades-long debate. A growing body of evidence suggests the core's spin has changed dramatically in recent years, but scientists have remained divided over what exactly is happening -- and what it means. Part of the trouble is that Earth's deep interior is impossible to observe or sample directly. Seismologists have gleaned information about the inner core's motion by examining how waves from large earthquakes that ping this area behave. Variations between waves of similar strengths that passed through the core at different times enabled scientists to measure changes in the inner core's position and calculate its spin.
"Differential rotation of the inner core was proposed as a phenomenon in the 1970s and '80s, but it wasn't until the '90s that seismological evidence was published," said Dr. Lauren Waszek, a senior lecturer of physical sciences at James Cook University in Australia. But researchers argued over how to interpret these findings, "primarily due to the challenge of making detailed observations of the inner core, due to its remoteness and limited available data," Waszek said. As a result, "studies which followed over the next years and decades disagree on the rate of rotation, and also its direction with respect to the mantle," she added. Some analyses even proposed that the core didn't rotate at all.
One promising model proposed in 2023 described an inner core that in the past had spun faster than Earth itself, but was now spinning slower. For a while, the scientists reported, the core's rotation matched Earth's spin. Then it slowed even more, until the core was moving backward relative to the fluid layers around it. At the time, some experts cautioned that more data was needed to bolster this conclusion, and now another team of scientists has delivered compelling new evidence for this hypothesis about the inner core's rotation rate. Research published June 12 in the journal Nature not only confirms the core slowdown, it supports the 2023 proposal that this core deceleration is part of a decades-long pattern of slowing down and speeding up. The new findings also confirm that the changes in rotational speed follow a 70-year cycle, said study coauthor Dr. John Vidale, Dean's Professor of Earth Sciences at the University of Southern California's Dornsife College of Letters, Arts and Sciences.
"Differential rotation of the inner core was proposed as a phenomenon in the 1970s and '80s, but it wasn't until the '90s that seismological evidence was published," said Dr. Lauren Waszek, a senior lecturer of physical sciences at James Cook University in Australia. But researchers argued over how to interpret these findings, "primarily due to the challenge of making detailed observations of the inner core, due to its remoteness and limited available data," Waszek said. As a result, "studies which followed over the next years and decades disagree on the rate of rotation, and also its direction with respect to the mantle," she added. Some analyses even proposed that the core didn't rotate at all.
One promising model proposed in 2023 described an inner core that in the past had spun faster than Earth itself, but was now spinning slower. For a while, the scientists reported, the core's rotation matched Earth's spin. Then it slowed even more, until the core was moving backward relative to the fluid layers around it. At the time, some experts cautioned that more data was needed to bolster this conclusion, and now another team of scientists has delivered compelling new evidence for this hypothesis about the inner core's rotation rate. Research published June 12 in the journal Nature not only confirms the core slowdown, it supports the 2023 proposal that this core deceleration is part of a decades-long pattern of slowing down and speeding up. The new findings also confirm that the changes in rotational speed follow a 70-year cycle, said study coauthor Dr. John Vidale, Dean's Professor of Earth Sciences at the University of Southern California's Dornsife College of Letters, Arts and Sciences.
Try harder Gaia (Score:3)
You ain't reversing this train.
Re: Try harder Gaia (Score:2)
But we've already seen this movie:
https://imdb.com/title/tt02988... [imdb.com]
It was the one where DJ Qualls used phreaking skills to bribe a government official.
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Yes, we have, and it was awful. And not the enjoyable awful.
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To each his own, it is not actually that bad from an acting, technical, etc... perspective. It won't win any Oscars, but I wouldn't call it awful. It is rather typical for a disaster movie, maybe a bit above average.
Of course, it is not what this movie is known for. What it is known for is its terrible science, but it definitely falls into "so bad it's good" territory. There are entire websites dedicated to it, it is at the top of many lists, and people still watch it, sometimes repeatedly for this very rea
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What it is known for is its terrible science
What "science"? It had less science that "The Boys".
It was a terrible action film with a typical Hillary Wank in the lead.
So THAT's why (Score:2)
This explains a lot about Washington these days!
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Nothing that magnets, sharks, batteries, and Uncle Bozie can't fix.
This could affect leap seconds too (Score:5, Interesting)
See this graph [navy.mil] showing how the earth's rotation has drifted relative to atomic clocks since 2000. The discontinuities are where leap seconds were inserted to keep civil time within a second of the rotation. Since 2020 the curve has turned generally upward; if UT1-UTC makes it far past +0.5 then a negative leap second will be needed for the first time ever. Bet we'll see some good software bugs that day.
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Yes the core is important. But as under 1% of the Earth by volume, and about 2% by mass, the core isn't that important. Plus, for questions of angular momentum, the distance from the rotation centre is also important - which boosts the importance of surface events compared to deep events.
I
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This article [doi.org] says "since 1972, the angular velocity of the liquid core of Earth has been decreasing at a constant rate that has steadily increased the angular velocity of the rest of the Earth. Extrapolating the trends for the core and other relevant phenomena to predict future Earth orientation shows that UTC as now defined will require a negative discontinuity by 2029."
Seems like the professional scientists see the core change as the main factor here. Earthquakes have some effect but some will slow the
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And the paper cited in TFS sees core changes as either having changed in trend, or possibly being cyclical (which is probably easier to explain than a secular change). Which adds up to two groups with differing ideas both observing a continuing experiment, and likely to both interpret the next several changes as support for their camp.
In practical terms, from the PoV of astronomers and NTP administrators, consider this : a b
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a big earthquake could have happened 5 minutes ago which would force a negative leap-double-second on New Year's Day coming.
"NO leap second will be introduced at the end of December 2024. [navy.mil]"
Stop worrying so much about earthquakes. "The 2004 magnitude 9.1 Sumatran earthquake [...] shortened the length of day by 6.8 microseconds. [archive.org]" So that extreme event caused a change of just 2.5ms per year. Any earthquake capable of causing a 500ms change in under 6 months would be, by far, the biggest in history.
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Earth says "Hold my beer. I hear hubris [wikipedia.org] , and we know what happens to people who display hubris!"
(Traditionally, the gods drive hubristic humans mad first, then torment them to a miserable, horrible, shameful death (e.g. Jason of the Argo, Oedipus), followed by an eternity doing something horrible in Hades (Tantalus thirsting and hungering eternally ; Sisyphus rolling the rock). Gods could neither die nor go mad, so Pr
So The Folks In The Inner World (Score:2)
Are trying to fuck us now. Maybe all that radioactive waste we buried made it down there and turned them into super mutant geniuses.
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They'd better be super robust geniuses.
Temperature in the inner core is about 5,200 Celsius (9,392 Fahrenheit). The pressure is nearly 3.6 million atmospheres (atm). Earth's Core [nationalgeographic.org]
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I've never been down there so I wouldn't know. Is there a webcam down there? As far as I knew the deepest hole humans have drilled into the earth is about 40,000 meters.
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40k feet, 12000 meter
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Feters, Meets. What the fuck ever. Both express the same percentage of depth relative to Earth.
Re:So The Folks In The Inner World (Score:4, Funny)
Use the proper units. The hole is 32 Empire State buildings deep.
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What makes it speed up again?
As I understand it, the metallic inner core is dragged by the Earth's magnetic field, generated by currents in the outer core (which spins faster). I would expect friction between the inner core and the rest of the mantle (which moves faster than the inner core at this time) should accelerate the inner core's rotation as well.
Headline is misleading (Score:5, Informative)
No, Earth's core is not spinning in the opposite direction. It's moving (slightly) slower than the crust.
Re:Headline is misleading (Score:4, Informative)
That is the same thing, just observed from a different frame of reference.
Re:Headline is misleading (Score:4, Insightful)
You and I get that. Many people don't and were assuming the core is now spinning in the opposite direction to the crust.
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That is the same thing, just observed from a different frame of reference.
It's true, however It's also not how most people understand this statement - confirmed with all the BS in the media. The core doesn't move backwards it spins just slower than the crust but still rotating the same direction as the whole planet.
I'd hope to avoid this troublesome trend of "click-bites" and misleading titles on /.
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It is actually different. In terms of relative, linear velocity, it is correct that the nearest part of the core to a particular point on the surface, it is moving backwards, but then the furthest part of the core from that point is moving in the same direction. The aggregate motion of the core linearly relative to the any point on the surface is zero, so it is not even the core that can be said to be moving backwards. Moreover spinning is angular velocity, not linear, and it is not spinning backwards, it i
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Was reading it is a regular cycle, might be 80 year IIRC. Caused by electro-magnetic interactions, the core is a big generator.
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What is storing - then releasing energy, and through what forces? Good questions!
If only there weren't 4500km of solid rock between us and the core, it'd be an awful lot easier to see what is going on. The famo
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Fun with geophysics. (Score:2)
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Like the rest of the planet, the core is cooling - slowly. As the primordial heat of assembly of the planet radiates away, and the fly-by-night radiogenic nuclides (U-235, U-238, K-40) decay away, the temperature is going down. Which is probably why the solid inner core has been growing for a billennium or two.
But yeah - all that damned rock gets in the way. It's hard to study. Fascinating though.
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Supposedly, yes.
But any vaguely sane-sounding estimates for volume-convected-per-year (for which, we can get some sane figures, from surface motions) has the mantle turning-over multiple times between then (Earth-formation+~100 Ma, with a fair error bar) and now ... so surely the impactor debris should have been mixed in several cycles ago. That's an argument used by the people who think the low
Bad news (Score:2)
The days will get longer and we'll have to work more.
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So it tracks (Score:4, Funny)
Our species' IQ?
Global warming (Score:1)
I would love to know (Score:1)
I would love to know how it was/is determined that the core is solid metal and not liquid metal.
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Unfortunately, the information is buried in the jargon. Like other sciences, you're expected to have a basic familiarity with the field - it's a paper, not a text book.
In this case, the magic term is in the abstract :
The Serbo-Croat swearword actually describes a serie