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.'"

New York Times? Why??????????

[Anonymous Coward]

How about New Scirntist's [newscientist.com] coverage? Or LiveScience.com [livescience.com]?

No bugmenot required, and they're science sites.

Slashdot gets more retarded every day, I swear.

(this post's mind-reading captcha="resorts")

Re: Easily Explained

[Black Parrot]

> No, it's clearly intelligent spin.

FYI, Intelligent Spin (notice the capitalization, please!) is just a special case of Intelligent Falling [theonion.com].

Shoulders of giants, kind of thing.

Re:It is not so simple.

[CoderBob]

It is gravitation that tends to cause the spin to slow down. The moon is locked into a 1:1 ratio of rotation:revolution, so it always presents the same "side" to the earth (no, not the "dark side of the moon v. light side of the moon bit. Even when the moon is a waning crescent, it is presenting the same surface features towards the Earth).

What will be interesting for Earth is to see which of the two largest bodies in terms of gravitation wins out, or if there will always be some form of resonance. Will we always present the same portion of Earth to the sun, so that one side of the planet bakes while the other freezes (which I believe is where Mercury is headed. Try going here: http://www.mira.org/fts0/planets/092/text/txt001x. htm [mira.org] for a description of Mercury's rotational period), or will we always present the same surface to the moon while we orbit the sun?

Re:Revolutions

[beefstu01]

This just in: the center of a 12" record travels at a greater number of RPMs than the outer edge. Reactions from the Doobie Brothers were not reported

Uh... no. The tangential velocity at the edge is much greater than the tangential velocity in the center. Both points have the exact same angular velocity, otherwise the record would break into many pieces. Silly boy, don't you remember Physics I?

Re:first post

[Timberwolf0122]

Close but wrong, the earth rotation is being slowed down by the moon or rather it is being slowed down by the Earth speeding up the moons orbit (hence the reason it get about a meter further away each year).

Science part: The earth is not perfectly round and is slightly pulled out where the moon is, now because the earth is rotating faster than the moon is orbiting this buldge is actualy occures slightly infront of the moon, the result is the moon gets pulled. This effect slows earth rotation and speeds up the moons orbit.

Re:first post

[Anonymous Coward]

This may come as a surprise, but space is not a vaccuum. There is quite a bit of miscellaneous matter floating about in space, and while the impact is small, over millions of years the inevitable physics is that rotation slows down.

Tidal Drag

[TrekkieGod]

The effect of gravity of the moon (and really all other objects in the solar system, to a smaller scale) on the earth as they rotate. Tidal dragging is the reason why the moon has locked its rotation with the earth (so that it always faces us).

Another obvious cause

[gr8_phk]

Every time a heavy chunk of crust breaks free and sinks into the liquid, it's like the skater pulling their arms in - it spins faster. Momentum is conserved, but at the shorter radius this translates into higher angular velocity. All the heavy stuff is in the center, and it must have spun up when that first happened. Is the difference still there, or is the process still happening a little bit?

Re:Are we due for a reversal of the poles?

[dwhipp3980]

What you heard on Discovery is correct. It has been postulated that the flow of the fluid outer core, and subsequent motion of ions within that fluid is responsible for the generation of Earth's magnetic field and geomagnetic poles. It has also been shown that the polarity of the dominantly dipolar magnetic field reverses, seemingly randomly through Earth's history. I'm not sure of the statistics you mention, but if in fact the average pole reversal period is shorter than the time during which the current polarity has been maintained, you should also consider the standard deviation of the reversals, which is huge. For example, during the Cretaceous geologic time period, there was a long period of normal (or similar to today) polarity known as the Cretaceous long normal. Geologic records show no reversals over this 43 million year time period.

Re:extinctions

[Anonymous Coward]

It's your job to supply credible sources for extraordinary claims, friend. The Sun's field flips every 11 years, AND I'M STILL HERE.
It's so very apt that the "To confirm you're not a script, please type the word in this image" word is "contempt"!

Re:It is not so simple.

[CheshireCatCO]

The Moon's tides are about twice as strong as the Sun's. (Which is why spring and neap tides occur in the first place.) It's a bit surprising that they're that close, but the Moon's proximity almost balances the Sun's killer mass. (And recall that tidal forces fall off like 1/r^3, so distance is more important here than for gravitational force where the Sun kicks the Moon's non-existent ass.)

What this means is that in around 45 billion years Earth will have a spin period of around 47 days and will be locked in a 1:1 spin:orbit resonance with the Moon (just like Pluto and Charon are now). Then something very cool happens: the Moon starts approaching Earth again and the Earth's spin continues to slow as it tries to match period with the Earth's orbital period.

Of course, we'll probably be long gone by then, what the Sun's red giant stage and all. But still, pretty cool.

(For more on these and other fascinating topics in solary system dynamics, check out Murray and Dermott's book.)

Re:extinctions

[vertinox]

I'm not sure about the parent or grandparent, but its not the field that I am concerned about, but the Cosmic Rays that the Earth's magnetic field may sheild us from.

If you aren't familiar with Cosmic Rays:

http://en.wikipedia.org/wiki/Cosmic_rays [wikipedia.org]

And IBM even has done reasearch on what Cosmic Rays does to electronics:

http://www.research.ibm.com/journal/rd40-1.html [ibm.com]

http://www.research.ibm.com/journal/rd/421/ziegler .html [ibm.com]

Think of it like an EMP bomb. The flip wouldn't give us enough radiation from cosmic rays to maybe kill us, but it's speculated that while its in limbo it would be enough to flip electrons in memory and kill sensitive electronic equipment.

Re:Hmmm...

[multi io]

If you have to introduce 1 leap hour or 3600 leap seconds in 600 years, all that means is that the *average* length of the mean solar day during that time was 1hour/600years=~2e-7 longer than 86400 sec. How much of that elongation was actually caused by the earths's rotation slowing down, and how much was caused by, say, the fact that the rotation was a bit too slow from the start, is a different question.

Now, AFAIK it happens to be the case that the definition of the second in the 1960s was indeed a bit too short with respect to the length of the mean solar day even back then, so the fact that the earth's rotation was too slow from the start will be the dominating contributor to the introduction of leap seconds for the next few centuries at least.

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

[fatted]

Problem solved.
http://www.ucd.ie/ucdnews/apr00/mystery.htm [www.ucd.ie]

or for people who like equations:

http://www.copernicus.org/online-papers/EGS/NPG/20 02/3/npg-9-373.pdf [copernicus.org]