Earth's core rotates both directions

  • Thread starter Dotini
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  • #1
Dotini
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Research indicates the Earth's magnetic field drives contra-rotating solid and liquid cores. Interaction between the two layers is believed to generate the Earth's magnetic field. Somehow that sounds funny, but I guess it must be so.

“The magnetic field pushes eastwards on the inner core, causing it to spin faster than the Earth, but it also pushes in the opposite direction in the liquid outer core, which creates a westward motion.”
http://www.leeds.ac.uk/news/article...r-old_problem_the_dynamics_of_the_earths_core

http://www.pnas.org/content/early/2013/09/13/1307825110
The associated electromagnetic torque currently is westward in the outermost outer core, whereas an equal and opposite torque is applied to the inner core. Decadal changes in the geomagnetic field may cause fluctuations in both these effects, consistent with recent observations of a quasi-oscillatory inner-core rotation rate.
 

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  • #2
D H
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Given the thread title ("Earth's core rotates both directions"), I think you are misreading. The paper is claiming that the inner core rotates slightly faster than one revolution per sidereal day while the outer core rotates slightly slower than one revolution per sidereal day. The inner core, outer core, and mantle all rotate in more or less the same direction, however.
 
  • #3
Dotini
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Given the thread title ("Earth's core rotates both directions"), I think you are misreading. The paper is claiming that the inner core rotates slightly faster than one revolution per sidereal day while the outer core rotates slightly slower than one revolution per sidereal day. The inner core, outer core, and mantle all rotate in more or less the same direction, however.
Okay. I was merely quoting from the article. Sorry for the misreading.
http://www.huffingtonpost.com/2013/...rd-westward_n_3941183.html?utm_hp_ref=science
 
  • #4
D H
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Expletive deleted newsies!

The paper's authors talk about a slow westward drift over hundreds of years. That's not spinning in the opposite direction. It's just spinning a tiny bit slower than the Earth as a whole.
 
  • #5
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presumably creating friction and heat
Could that be quantifiable?
 
  • #6
Chronos
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The core increases in temperature with depth. It is entirely logical the cooler outer layers, being more viscous, suffers more drag than deeper, hotter layers, which are less viscous. Modeling this is quite a challenge.
 
  • #7
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Momentum coupling betwee core and mantle due to friction is weak. However I believe it is strong enough to explain the length if day variations andnutations observed.
 
  • #8
Baluncore
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All things are relative. The title “Earth's core rotates both directions” is meaningful when considered from a point on the Earth's surface.

The temperature of the core is above the curie point so any "core supported" magnetic field must be due to a circulating electric current.

How do we know that it is the core rotating and not the axis of the electric current. The measurement of Doppler shift for multipath seismic waves is a possibility.

I would expect very slow changes in the current because of the high conductivity of the core material. What time constant is expected for a 1000km skin effect in a metal melt?

Could this be a big MHD machine where the current moves the core? Or maybe the inner core is the rotor of an induction motor/generator, where current flowing in the outer core drives or is driven by a solid inner core.
 
  • #9
The temperature of the core of earth is so much that feels like it rotate in opposite direction but in actual it rotate unidirectionally.
 

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