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

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    Administrator Aragorn's Avatar
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    Lightbulb Earth's inner core may have started spinning other way: study

    Source: Yahoo News




    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."


    Source: Yahoo News
    = DEATH BEFORE DISHONOR =

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    Senior Member United States Diabolical Boids's Avatar
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    I could swear I read somewhere in the pool of conspiracy theories and doomsday scenarios that a reversal of the earth's spin caused major upheavals in the earth's crust as it continues to cruise in one direction while the center reverses.

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    Senior Member Lord Sidious's Avatar
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    Quote Originally posted by Diabolical Boids View Post
    I could swear I read somewhere in the pool of conspiracy theories and doomsday scenarios that a reversal of the earth's spin caused major upheavals in the earth's crust as it continues to cruise in one direction while the center reverses.
    You might be thinking of the reversing of the poles
    Ní siocháin go saoirse

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    Senior Member Fred Steeves's Avatar
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    Reminds me of the old adage of blind men touching different parts of the elephant, thus coming to different conclusions as to what it is.
    The unexamined life is not worth living.

    Socrates

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    Administrator Aragorn's Avatar
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    Quote Originally posted by Diabolical Boids View Post
    I could swear I read somewhere in the pool of conspiracy theories and doomsday scenarios that a reversal of the earth's spin caused major upheavals in the earth's crust as it continues to cruise in one direction while the center reverses.
    Well, no, that which you are referring to doesn't have anything to do with the direction of spin of the iron core, but with a presumed and unrelated shift of the Earth's mantle, for which there is some (arguably disputable) evidence that it may have happened several times already in the past.

    For instance, there are maps dating back to the middle ages — created approximately between the 15th and 16th century — that show a fairly complete outline of Antarctica's coastlines as they exist without its ice cap, which suggests that Antarctica may have been located somewhat closer to the equator during that time. Given that there's not enough tectonic activity between the southern part of Africa and Antarctica to account for that much continental drift over such a short period of time, there is the theory that Earth's mantle as a whole may have shifted instead.

    The paranoid belief — I'm not going to call it a conspiracy theory, because there are no potential conspirators involved — would be that this shift happens suddenly, and as such, with cataclysmic consequences. If this were indeed to happen in that manner, then massive tsunamis and earthquakes would probably wipe out 95% of all life on Earth. But in reality, some gradual displacement of the mantle could indeed take place over a long period of time due to the outer crust of the planet floating on a molten iron core.

    A somewhat similar phenomenon that's much better understood and scientifically acknowledged is the continental drift of which I spoke higher up already. At present time, the Americas and Eurasia are drifting farther apart by a few centimeters every year due to tectonic activity, mostly caused by underseas volcanoes and fissures. Or otherwise put, the Atlantic Ocean is getting wider every year, and the Pacific Ocean is getting narrower every year.

    But, see my reply to the Sidinugget below.





    Quote Originally posted by Lord Sidious View Post
    Quote Originally posted by Diabolical Boids View Post
    I could swear I read somewhere in the pool of conspiracy theories and doomsday scenarios that a reversal of the earth's spin caused major upheavals in the earth's crust as it continues to cruise in one direction while the center reverses.
    You might be thinking of the reversing of the poles
    Well, a periodic reversal of the magnetic poles is real, and this is related to solar activity. The sun is bombarding the Earth with electrically charged particles every minute of the day, and if and when this bombardment exceeds a certain threshold, then the electromagnetic field of the Earth may indeed be flipped. Furthermore, Earth's magnetic poles also shift over time, because the magnetic north and south poles have already for a long time no longer corresponded to the geographical north and south poles respectively. At present time, Earth's magnetic north pole is situated somewhere in Siberia.

    However, due to the scientific illiteracy within the paranoid conspiracy-theory community, the concept of a magnetic pole reversal got tied in with the theory about a sudden geographical pole reversal, which would — as I described above — be a cataclysmic event. But that's just the scientific illiteracy at play, because the displacement of Earth's mantle by whatever extent and over whatever amount of time has nothing whatsoever to do with the orientation of Earth's magnetic field, and Earth is not suddenly going to flip upside down, let alone shriek to a halt and start spinning in the other direction.

    What the change in spin of Earth's iron core does have an effect on is how fast Earth is spinning around its north-south axis, or otherwise put, the length of a day. In overall, Earth's north-south axis spin has slowed down a great deal since Earth was formed. During the time of the dinosaurs, a day on Earth lasted only about 20 hours, versus 24 hours today — and this also means that the experienced gravity has been increasing over time due to the diminished centrifugal effect at the surface.

    But at the same time, it has been observed in recent times that Earth's spin has been speeding up again for quite a while already, and as such, this observation would corroborate the theory that the super-rotation of the core — which is spinning much faster than the mantle — has now accelerated again and is speeding up the spin of the mantle as well due to friction.
    = DEATH BEFORE DISHONOR =

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    Senior Member Lord Sidious's Avatar
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    Quote Originally posted by Fred Steeves View Post
    Reminds me of the old adage of blind men touching different parts of the elephant, thus coming to different conclusions as to what it is.
    Sounds like a game the navy would play at the equator............

    Song for that aragornugget

    Ní siocháin go saoirse

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    Super Moderator Wind's Avatar
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    Seems that this is the right place to post this.


    Source: https://www.youtube.com/watch?v=8GahanWVCJM
    "The more I see, the less I know for sure." ~ John Lennon

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