Earth's Core Spins Faster than Earth

Dreamwalkerofyore writes "The New York Times has an article on a recent affirmation that the earth's core rotates faster than the earth proper. From the article: 'Confirming assertions first made in 1996, a team of geophysicists are presenting data in the journal Science today showing that the earth's inner core... spins faster than the rest of the planet. Over a period of 700 to 1,200 years, the inner core appears to make one full extra spin. That extra spin could give scientists information about how the earth generates its magnetic field.'"

first post

[muttoj]

Seems logic to me. The core is spinning and the outside of earth has drag to cope with.

Military applications

[Kawahee]

I don't see how this could be all that technologically useful for consumers, but for the military, I'd like to see little plastic spheres that, when twisted, generate their own little magnetic fields without any other materials than what the enemy would expect to be naturally residing in an area. Drop a few around a desert or combat area, and watch their compasses/electrical equipment go out.

Hmmm...

[gowen]

Given that the Earth's rotation is slowing down, isn't it immediately apparent that the liquid core must spin faster than the outside. It's just basic fluid dynamics. If apply a torque to the outside of a fluid filled region, the middle of that region will feel the effect last.

Will the Earth cease to have magnetic poles?

[ReformedExCon]

If the core slows down due to friction with the mantle, will there be an effect on the magnetic field surrounding the Earth? Without the magnetic field, my understanding is that the Van Allen radiation belt will also not exist, and that in turn would expose the Earth to the full-on radiation of the Sun.

I'm no scientist, of course. But I wonder what the implications of the spinning core means. Also, how long would it take to stop spinning, or to develop a wobble?

There have been a slew of large earthquakes around the world lately. Could it be related?

Re:Military applications

[Anonymous Coward]

If we could cheaply generate fields that strong, we would not need nuclear power plants, we could generate all the energy we need using induction.

Re:Give my regards to the Earth's core...

[aussie_a]

So I'm just wondering: does this delta-omega have anything to do with the fact that the Earth's magnetic field reverses itself every 200,000 years or so?

Well, according to Wikipedia [wikipedia.org] why the reversal happens isn't well understood, so it very well could be. However there are some hints that this is the case in the Geomagnetic excursion page [wikipedia.org]:

The dominant theory is that they are an inherent aspect of the dynamo processes that maintain the Earth's magnetic field. In computer simulations, it is observed that magnetic field lines can sometimes become tangled and disorganized through the chaotic motions of liquid metal in the Earth's core

I'd suggest looking for more authorative sources if you're truly interested.

Please begin rampant conjecture and wild speculation.

Don't mind if I do. From Geomagnetic reversal at wikipedia [wikipedia.org]:

homo erectus and their ancestors certainly survived many previous reversals. There is no uncontested evidence that a magnetic field reversal has ever caused any biological extinctions.

Makes me wonder how geomagnetic reversals coincide with the speciation and evolution of our ancestors (or any animals). The extra radiation might not have killed them, but it certainly could have mixed things up, create higher then normal mutation rates. The last one was 780,000 years ago. Homo sapiens sapiens hasn't ever existed while there's been a geomagnetic reversal. It could be that by the time we came around, the mutations had died down to a normal rate.

Mars magnetic field's hiding?

[aussie_a]

I wonder what the rotation rate of Mars' core is. We know [planetary.org] it's either liquid or solid and liquid (the latter being what Earth has), so it could have a difference, which would create a magnetic field. Only problem is, Mars doesn't have a magnetic field. However, Mars' field might also be hiding, as it does on Earth when changing the north and south poles [wikipedia.org] which can take hundred to thousands of years. Now we've only been watching Mars with any sophistication for decades, which means Mars could have a field that's currently undergoing a reversal. If it isn't undergoing a reversal, and the two rotations are different, then it would prove enlightening on why that is the case.

It also bounces.

[kulakovich]

The Earth's core also bounces from North to South. Not sure if it is a remnant of the colision that formed the Moon, or part of its conservation of momentum from the outer crust trying to change it's vector, the core being a giant defacto gyroscope.

Eventually I will post the math. =)

kulakovich

Re:one BILLION amps

[SheeEttin]

If you get an antenna big enough (e.g. 200 ft), you will find that there is quite a lot of energy flowing through it, and if you want to use it for anything, you'll have to ground it.

Reversal happens like a dynamo with a loose rotor

[crovira]

There's a threshold where the fields around the rotor get disorganized (expect geomagnetic migrations to get all screwed up,) and then field lines reverse as the threshold is crossed.

Nothing actually happens to the rotor (it doesn't spin backwards all of a sudden) but the field lines generated are inverted.

Re:Hmmm...

[Thagg]

And what's potentially going to be *really* interesting is that earth is going to slow down fairly dramatically over the next few hundred years, according to US scientists. Note the article a few days ago in Slashdot [slashdot.org] about the US government lobbying to get rid of the leap second, and just have a leap hour every 500 or 600 years. If you do the (very simple) math, you can see that these scientists anticipate the earth rotation rate slowing down by five or six seconds a year over that time.

My guess is that this is due to global warming, and the earth (particularly the oceans) getting farther from the spin axis -- both by just expansion due to increased temperature and from land-locked ice melting into the ocean (especially from Greenland.)

So, whatever effects that are caused by the differential change in rotation, will be exacerbated at least another 20% or so.

Oh, and the earth's inner core (the part that the FA describes as rotating faster) is solid, not liquid. The solid inner core is lubricated by several hundred miles of liquid outer core from the rest of the planet.

Thad Beier

Yes, insightful

[freeweed]

As another poster pointed out, sarcasm is often insightful.

What Smidge has pointed out (quite nicely, I must say) is that pretty much EVERY scientific theory/explanation can be trivialized in this matter. Let's face it, here's what ID boils down to:

1. The world, and everything in it, are complex. No one would argue this.

2. In trying to understand complex things, we might miss some details, or in fact most of the detail. Again, no one would argue this.

3. Because we can't claim a perfect, 110% understanding of something, there's simply no way we can ever understand any of it. Logical fallacy. However, because of this:

4. Therefore everything was created by God. Everything is the way it is because of God. Otherwise how could things be this way?

Oh, and

5. My theory's as good as yours, because I say so, and yours is quite frankly far to complicated to understand whereas mine is simple and therefore correct.

#3 is WHY ID is not 100% laughed at by people, and #5 is why it's accepted so widely.

Re:Give my regards to the Earth's core...

[Thrymm]

The Earth is also cooling, albeit at a very slow rate correct? Thus the Inner Core should be growing larger as the molten core cools one would think.. ie: Mars with only a solid core.

One other question I do have, is the core all iron? What about the heavier metallic elements such as Uranium which is decaying, etc....

Re:Give my regards to the Earth's core...

[Ungrounded Lightning]

what will be interesting is if someone can figure out not only the speed, but also the direction of the spin. There's no guarantee that the inner core is actually spinning along the same axis as the mantle/crust.

Sure there is: Fluid Friction. Only convection (like atmospheric or oceanic weather phenomena but at geologic time scales) and forces from the dynamo are likely to have any non-straightforward effect, and those will be minor deltas.

The basic mechanism is obvious: The planet is spinning. The core is molten while the crust is essentially solid. There is a massive moon, orbiting above synchronous orbit and creating tidal drag. The tidal drag slows the rotation and raises the moon's orbit. The tidal braking force is strongest at or near the surface of the planet and vanishes at the center.

With braking at the outer layers the core spins a tad faster, but in the same direction and (with the braking very small compared to the fluid fricton) ALMOST exactly at the same rate - the difference is about one turn in 300,000 (assuming the middle of the article's range).