Is The Earth's Rotation Changing? 372
Roland Piquepaille writes "We all know about the current controversies associated with the ozone layer or the global warming phenomenon. Now, the NASA's Earth Science Enterprise (ESE) is warning us that atmospheric changes or El Niño events can affect the Earth's rotation. During El Niño years, for example, the rotation of the Earth may slow ever so slightly because of stronger winds, increasing the length of a day by a fraction of a millisecond. David A. Salstein, an atmospheric scientist from Atmospheric and Environmental Research, Inc., led a recent study about this possible effect. Salstein looked at meteorological and astronomical measurements from different sources and found they were in good agreement. Check this column for a synthesis. For technical explanations, images and animations, please read this NASA paper, Changes in the Earth's rotation are in the wind."
well known (Score:5, Funny)
since 1900 (Score:5, Insightful)
Re:well known (Score:5, Funny)
A flat earth, it's not just a good idea; it's the truth.
Simple (Score:3, Funny)
Re:well known (Score:3, Funny)
Obviously, you are not nearly up to the state of science in Earthism. Of course the world is both flat and round (think a round piece of cardboard). And it rotates around the earth axis, which is mouted under the temple rock in Jerusalem (you did know that the middle of the earth is in Jerusalem, right?).
Now, in El Nino years, all the scientists move to South America to study the phenomenon. South America is on the outermost fringe of the flat world (as is North America), hence they move mass from near the center (Europe) to the fringe. So to maintain angular momentum, rate of rotation has to slow down.
Now since this information is out, more scientists are going to study El Nino, of course, making the problem worth. And once the US scientists (being slightly slower and always behind) notice this and flock to Peru to, we can even expect the world topple over. If George Bush were slightly smarter, he would move troops to South Korea, to balance things. Moving them to Iraq helps with the rotation problem, but not with the toppling problem...
Re:well known (Score:2)
Yeah, but at least it's not a dupe. . .
Days getting longer? (Score:5, Funny)
Re:Days getting longer? (Score:3, Funny)
Re:Days getting longer? (Score:2, Funny)
Ill bet my bastard boss is gonna try and get that time outa me too!
Bah - I change the earth's rotation regularly (Score:3, Funny)
Conservation of angular momentum.
PS3 consequence? (Score:2, Funny)
Beans! (Score:2, Funny)
And I thought the day only felt longer after eating at a Mexican restaurant.
Re:Beans! (Score:2, Funny)
And I thought the day only felt longer after eating at a Mexican restaurant.
I think it's clear that the real culprit is windmills. If wind pushing on the Earth makes its rotation slow down, it logically follows that the more surface area to be pushed on, the greater the effect, whether or not you eat Mexican food. This means that those giant canvas sails on windmills aren't just grinding grain for Dutchmen in their clogs, they're lengthening the day! I've seen many other posts here lauding the extended day for a variety of reasons, but a longer day is simply no good, as Sealab 2021 is already shown on TV far too infrequently, and those fractions of a millisecond add up over the course of a week! Our only possible course of action: demolish all windmills, so we can see our delicious animation seven fractions of a millisecond sooner every week. Yup, no choice but to destroy all windmills... and that damn Sydney opera house.
SUPERMAN! (Score:5, Funny)
Re:SUPERMAN! (Score:2, Funny)
What they're saying is that now, we don't NEED a mythical being like superman to accomplish time travel. Now, we can just release some really fucked up greenhouse gasses and eventually mess with air currents enough that time travel will be easy and real.
I wouldn't buy my voodoo 3 either.
Re:SUPERMAN! (Score:2)
I would buy all of microsofts stock, do a nasty hostile takeover, and then bankrupt it
Just to stop the the terminator-like future which comes as a result of the current microsoft
Re:SUPERMAN! (Score:3, Funny)
Oh great, (Score:2, Insightful)
Re:Oh great, (Score:5, Funny)
This is clearly a problem with SUVs. A vehicle as heavy as an SUV puts down a trememdous amount of torque when it moves, and this action, combined with the great suburban conspiracy of living to the East of their workplace (you go faster going home, so more torque to slow down the Earth), are creating this problem.
Re:Oh great, (Score:3, Funny)
I mean if 25% are going due north, 25% due south, 25% east, 25% west then the net effect would be 0.
I'm more worried that people in North America are getting fatter, making the earth lopsided. So far it's just USA and Canada putting on the weight. Luckily those earth-conscious Mexicans are starving themselves to counter the effect.
Re:Oh great, (Score:2, Flamebait)
Karma to burn, baby (Score:5, Insightful)
Besides, I thought we were to all have died from Global Cooling by now, at least that was what they were saying in the 1970s. How did cooling switch to warming so fast?
Re:Karma to burn, baby (Score:3, Insightful)
That was scientific research (Score:4, Insightful)
Just because you don't want something to be true doesn't mean that it isn't true
And the reverse too. Of course they want global warming to be true, as they've based their whole being on that hypothesis. Disproving global warming to a green would be like disproving God to a Christian; both would result in a crushing blow to the psyche and massive denial.
Panic sells, and simply saying that the Earth has warming and cooling cycles doesn't. A lot of people have a lot to loose if it turns out the latest catastrophe fad is as valid as its predecessors.
Re:That was scientific research (Score:4, Insightful)
Let's turn it into an appropriate analogy and you'll immediately see the flaw:
People die of old age. Therefore, if someone just died, they died of old age.
Now see the problem? Murder, suicide, accident, none of those things exist in such a universe.
Of course they want global warming to be true, as they've based their whole being on that hypothesis.
Riiiight, I really want there to be flooding, disease, famine, and drought in my lifetime. That would be super.
Relationships and observations (Score:3, Insightful)
Young-Earth creationists also use inaccurate historical measurements (in this case, the speed of light) to bolster their argument.
I would also like someone to explain to me why all the pre-1970 data used to show a cooling trend, and now it's a warming trend.
Basically, there has been too much chicken-little science throughout the ages for me to hitch onto a catastrophism theory this young.
Wait a second... (Score:5, Funny)
Well, duh (Score:2)
By the way...when is the next pole shift due?
Re:Well, duh (Score:5, Funny)
http://www.poleshiftprepare.com/poleshift.htm
"I myself have outstanding personal knowledge and conviction that the cataclysms will occur in May 2003, which is why I am openly stating this on the Internet, and appealing to similar individuals who wish to take steps in preparing for it."
IT MAY SEEM FUNY NOW BUT U THANK HIM & HIS OUTSTNADING CONVICTION TO TELL US ON TEH INTRANET WHEN TEH POLE SHFITS MAY 2003!!!11 PREPAR URSELF!!!
^-- How my IQ dropped after reading his article... I guess it's the Internet we love and hate.
Superman? (Score:3, Funny)
This is news? (Score:2, Insightful)
Consequently the oceans slow the rotational period of the earth. I read about the physics of the tides twenty some years ago. The physics was clear then.
Should have known... (Score:2, Funny)
Would be only short term (Score:3, Insightful)
It seems like a reasonable enough argument that the rotation period of the earth would change during an el nino period. But once this the el nino effect had ended the rotation of the earth would have to return to normal, so any effect that might occur would be only short term. Also due to the large difference in the mass of the solid earth and the earths atmosphere, the change in the earths period of rotaion would be so small as to be unmeasurable and therefore unimportant.
Short Term? (Score:5, Insightful)
And what are you talking about with your statement about the change being "unmeasurable"? The point of the article is that it is being measured.
Wait a minute.... (Score:3, Funny)
When did life turn into a Hilary Swank action flick? [imdb.com]
OK, there's only one way to solve this ... (Score:5, Funny)
Everybody run east as fast as you can, to speed the Earth up again!
/me waits for hundreds of pedantic comments explaining why this wouldn't work
Re:OK, there's only one way to solve this ... (Score:3, Funny)
Re:OK, there's only one way to solve this ... (Score:2, Informative)
Re:OK, there's only one way to solve this ... (Score:2)
Re:OK, there's only one way to solve this ... (Score:2)
*cowers in shame*
Re:OK, there's only one way to solve this ... (Score:5, Funny)
Re:OK, there's only one way to solve this ... (Score:2)
If you run one way and have a heart attack, you're still fine as long as they don't bury you back where you started.
Getting bored and going home is bad though unless you start by going the wrong way, and then pick up a big juicy burger before oozing back.
So really, I think there's enormous potential in the
Re:OK, there's only one way to solve this ... (Score:5, Informative)
Everybody run east as fast as you can, to speed the Earth up again!
Disregarding the honest mistake (you need to run West, not East)... This would actually work, as long as everyone *keeps running*. As soon as they stop running, the angular momentum which was transferred to the Earth will be transferred back to the runners. You can't change the total angular momentum of the system.
In order to speed up the Earth you would have to use a rocket or some kind of cannon which is capable of flinging material *clear off* Earth's surface, never to return. Even then, the amount of energy contained in the rotation of the Earth is *astonishingly huge*. It's doubtful we'll ever come up with anything that could make even the slightest impact on it.
Old news? (Score:4, Interesting)
Does simply adding the words "El Nino" makes people think this is a new, important idea? The planet's rotation speed is also affected by the impact of meteors and space dust, but I don't see anyone publishing studies to measure that infinitesimal effect.
Re:Old news? (Score:2)
But what about the moon? (Score:5, Interesting)
If you really want to get agitated about the earth's rotation slowing down, consider the moon. Tides act as a brake on the earth/moon system. So the rotation of the earth slows, and the moon (to conserve angular momentum) moves ever so slowly away from the earth.
Re:But what about the moon? (Score:5, Informative)
This adjustment also important to us because it is of the same order at many locations as the change in sea level due to the temperature of the ocean.
Re:But what about the moon? (Score:3, Interesting)
There are two ways the earth's rotation can change: keep the same angular momentum by moving mass away from the axis, and throwing mass out into space with a more easterly velocity than it would have sitting where it started.
The study mentioned in the article isn't talking about a non-conservative change in the Earth's rotation, in any case, but rather a conservative change due to permanent (or, at least, long-term) climate change. If the winds blow harder, the Earth slows down; if the winds blow less hard, the Earth speeds up. If the winds continue to blow hard for the next millenium, it'll be a long millenium.
Re:But what about the moon? (Score:5, Informative)
No. Friction is a non-conservative force. The energy is irreversibly transformed into heat. *Total energy* is conserved, but there is no physical law saying that kinetic energy must remain kinetic, or rotational must remain rotational.
Imagine a bathtub full of water, with the water sloshing around in the bathtub. As the sloshing water rubs against the sides of the tub, it transfers energy to the tub in the form of heat. Eventually the sloshing ceases, and all the kinetic energy the water had is now converted to heat. The process is irreversible -- you don't suddenly see the bathtub *cooling down* as the water spontaneously starts sloshing again.
I mean, this is basic thermodynamics.
Re:But what about the moon? (Score:3, Interesting)
That is, it remains constant in a closed system. The only long-term changes to the earth's rotation come from the earth's angular momentum being transferred to the moon.
Re:But what about the moon? (Score:2)
I didn't say it was. I said *total* energy is conserved. This includes heat.
if you heat up the Earth, the athmosphere will expand, the earth's rotation will slow down, and the total rotational energy will increase -- but the angular momentum remains constant.
The effect they're talking about isn't due to increased rotational inertia from an expanding atmosphere. They are talking about fast winds exerting friction on the surface. You're correct in that the angular momentum transferred from the Earth ultimately ends up in the atmosphere, but the point I was making is that this transfer is not reversible. The angular momentum appears in the atmosphere as heat, and all the well-known efficiency theorems from thermodynamics apply to it.
Re:But what about the moon? (Score:2, Insightful)
Now, why milliseconds a year are important? I couldn't tell you; if this effect got bad enough to have a noticeable impact on any of us, the planet would be uninhabitable. It would take a lot of wind to speed up a planet.
Let's pay attention to the important news here, people. Like, will Sony ship a reasonable number of PS3s?
~SL
Mountains do the same thing (Score:5, Informative)
What's the average length of a day? Something like 23 hours, 59 minutes and 56 seconds or something like that. Which is why we have a leap year:
If the year is divisible by 4
Unless it's divisible by 100
But always if it's divisible by 400
So hey... leapYear = ((year%400)==0)||(((year%4)==0)&&((year%100)!=0))
Can someone answer this though: Do we manually synchronize our clocks every once and awhile (say every few years anyways) just to make sure? I heard a rumor about it (most people have to reset their clocks after the power goes out anyways, and PC clocks are horribly inaccurate), so is this true?
Re:Mountains do the same thing (Score:3, Informative)
Re:Mountains do the same thing (Score:2)
Very cool...
Re:Mountains do the same thing (Score:4, Interesting)
Are you referring to leap seconds [navy.mil]?
Re:Mountains do the same thing (Score:2)
For all that matter to our daily lives, earth's rotation is a almost round circle, that is, we don't get close/far away from the sun.
Re:Mountains do the same thing (Score:2)
What causes seasons is not distance from the sun. It is length of day and angle (and consequently concentration) of the suns rays on the surface. In winter time, the northern hemisphere is tilted away from the sun, therefore receiving more indirect rays. During the same time, the southern hemisphere is tilted towards the sun, making the rays hitting the surface more direct and concentrated.
Remember that when you are experiencing winter, the other half of the earth is experiencing summer.
Re:Mountains do the same thing (Score:5, Informative)
True, but when the snow melts in spring the rotation will speed back up again (rotational inertia decreasing as mass moves downward).
This is fundamentally different from wind friction, which is a non-conservative force which *irreversibly* slows the Earth's rotation. The only way it might speed up again is if the wind started blowing the opposite direction with equal force.
This happens more during the winter when the earth is farther away from the sun.
The Earth is *nearer* the sun in the Northern Winter. It is the tilt of the rotational axis which produces winter, not distance from the sun. The moment of closest approach (perihelion) actually precesses very slowly (arcseconds per year). In short, there is utterly no relationship between distance to the sun and the seasons we experience on Earth.
Do we manually synchronize our clocks every once and awhile (say every few years anyways) just to make sure?
It depends what kind of clock. The cesium clock is the scientific *definition* of a second, therefore it doesn't need to be calibrated since everything else is calibrated to *it*. How often you need to synchronize your clock depends on how accurate it is (usually measured in parts per million, or parts per trillion for accurate clocks).
Re:Mountains do the same thing (Score:2)
So what? (Score:2)
I'd say its more of a "curiosity".
Earth rotation is slowing continually... (Score:4, Informative)
This story is a plant advertising a movie (Score:5, Insightful)
Just like the last one planted by the same folks. Who? its a promo for the movie "the CORE" about what? the slowing rotation of the earth's core (caused by a secret weapon project).
the last one was also in slash dot too. its was on drilling to the earths core with advanced materials. (sorry I cant locate the slashdot article right now, though I did see the last one about the mars core [slashdot.org]
in that case the movie distibuter's publicity folks were using real science and real information. They were just responible for planting news articles about it strategically. this smells the same, and the timing makes it clear.
People banging on about el nino (Score:3, Funny)
Main topic. (Score:4, Insightful)
The main cause of the earth's rotation slowing _during EL Nino years_ is the change in the angular momentum of the earth. This means, that as some point, the angular momentum will change BACK!! Hence, CONSERVATION of momentum. The net effect in the long run is no change in the earth's rotational period due to this phenomenon.
However, it has been a well known fact that the earth's day will gradually grow longer. One of the causes of this is the earth becoming tidally locked with the moon, the way the moon is now. It's just a function of relative gravitational force.
And offtopic: The geologic record does indicate the magnetic poles reversing every 10k-12k years. You'll have to research the 'why' on your own though. I only remember from my astronomy classes that it does...
The truth is out there, but the server is down or not responding.
Re:Main topic. (Score:2)
I don't think the conservation argument applies, because the Earth is not a closed thermodynamic system. There is energy coming in from the Sun. If that energy is converted into ocean currents that cancel each other out all well and good, but if the currents start to flow more westwards than eastwards or vice versa, then the rotation can be affected in such a way that there's no guarantee that it will be reset.
Cause or effect? (Score:2)
If you two related things don't mean that the first named is the cause and the second one the effect, even if in theory one could make some impact in the other.
Does this mean .... (Score:3, Funny)
This is not news... (Score:3, Insightful)
Re:This is not news... (Score:2)
Title and teaser misrepresent article (Score:2, Informative)
2. The interaction between Earth (solid ground plus oceans) and atmosphere can only exchange each participant's orbital momentum; it does not change the total orbital momentum.
3. Therefore, large-scale atmospheric phenomena can accelerate/decelerate the rotation of the earth on slow timescales (months/years). They have no influence on the long-scale deceleration (cf. point 1). The main point of the article is that one can use this short-time correlation as a test of measurements of the atmosphere and numerics: The fact that the two vastly different systems, namely the meteorological and the astronomical, are in good agreement according to the conservation of angular momentum gives us assurance that both these types of measurements must be accurate.
What about wobble? (Score:2, Interesting)
A couple of things... (Score:4, Interesting)
Second, I find it kind of interesting the change in the way we percieve time. Centuries ago, the earth made a great clock. 24 hours was defined as a day, and if all of the sudden the day became longer, that longer period of time was defined as 24 hours. Now, we see that the earth makes a pretty bad clock (by today's standards), and rather than relying on the earth as our ultimate timepiece, we rely on atomic clocks. It seems strange: we have all of these time units like hours, days, months, years, etc., all defined first by astronomical methods, but now because of our (technological) ability to be more regular than the cosmos, the hour, day, month, year, etc. have sort of lost their origins.
Re:Some better things... (Score:2)
See, these original divisions are based loosely on astronomy, sure. But it was
People who want to use a decimal-based system for dividing time are morons.
Obviously the above post is phrased quite poorly, but I do hope that I managed to get my point accross.
I would have thought it'd be the other way around (Score:2)
So what? (Score:2)
Great (Score:2, Funny)
g
More Gravity? (Score:2)
Oceans (Score:3, Interesting)
I'm surprised no one else thought of this yet... (Score:2, Insightful)
I don't know, I just a geeky chemist with wild ideas.
There's a lot of speculation going around (Score:3, Interesting)
Somebody please do the math of how that would affect angular momentum.
Do your part! (Score:2)
All together now... (Score:5, Funny)
Face east, and...
BLOW...
now face west and...
SUCK
New technology? (Score:2)
Accuracy & Precision (Score:2, Insightful)
Give us those error bars guys, than we can talk.
Root Cause (Score:3, Funny)
hmm.. (Score:2, Insightful)
leap seconds keep noon at noon (Score:3, Informative)
All of these measurements are made under the purview of the International Earth Rotation Service [iers.org]. There are models for all manner of astrophysical and geophysical effects considered in the Conventions [navy.mil] that are used when reducing the data.
The way that solar noon is kept at civil time noon is by inserting leap seconds. In most places civil time is offset directly from UTC [iers.org]. When a leap second is inserted the day is 86401 seconds long.
This irregularity upsets some kinds of timekeeping systems, and as a result there has been discussion that leap seconds should be abolished. That would cause noon to drift away from noon. That may not be a good thing [noao.edu].
Slow down due to space dust (Score:3, Insightful)
We need a space vacuum to suck up all of the dust before it gets here...wait a minute, space is already a vacuum!
Every week (Score:5, Funny)
constants (Score:2)
Ice age(s) anyone?
Screw Rotation Speed, Worry about THIS (Score:2)
Consider precession [cornell.edu], where the Earth's north axis slowly moves along the celestral plane like a slowing top, which changes what star we consider to be our "North Star." I believe Vega was closer to being the North Star some 15,000 years ago.
A more dire event: When the magnetic poles shift or trade places. That probably wasn't an event way back when except for migratory animals, but today with all of our electronics, it could be interesting to see what effect a shift would do to a computer or compass.
Or, maybe we should worry more about the Mets or the Cubs. Or if our martinis were shaken and not stirred...
The main cause is tides from the Moon (Score:4, Interesting)
The Moon was certainly closer at one time -- Robin Canup, who works down the hall from me, has done some fabulous simulations of the formation of the Moon (thought to be from a giant impact of two planetoids; the larger fragment evolved into the Earth, while the smaller one became the Moon). She claims that Moon must have formed right around the Roche limit (the distance at which it would just barely not be pulled apart by tides). If that's so, then it would have had an orbital period of about 6 hours. Meanwhile, the Earth would have been rotating faster yet.
The ongoing tidal drag is evident in the "leap seconds" that some international committee periodically adds to atomic time to get coordinated universal time. The leap seconds are becoming more frequent, because (surprise) the day is slowing down a microscopic but measurable amount compared to its speed in 1951. (One leap second per three years corresponds to a proportional change of only 1 in 10^8 [100,000,000], so no wisecracks about sleeping in late, please!
It's a good thing ... (Score:2)
Yeah, well... (Score:4, Interesting)
Sadly, the fact that gasses (identically to liquids) can create drag on any body within them is far from new, startling or amazing.
In fact, here are a few other trivial points:
None of this stuff is outside the scope of an A-level student taking maths and physics. The chances are, though, they won't get 5-figure paychecks for coming up with such trivia.
The answer, my friend... (Score:3, Funny)
Dont't worry, these guys are in charge. (Score:4, Informative)
Uniformitarianism is dead, already. (Score:3)
established _repeatedly_ now. The energy coming in from the Sun
(and trace amounts from other sources) is not without effect, duh.
So of _course_ stuff changes. Yeah, the earth's rotation changes,
its inclination to the eccliptic changes, it's orbit changes, its
mass changes, the distance to the moon changes, the composition
of the atmosphere changes, the chemical content of any given
rock changes, et cetera. Uniformitarianism is an interesting
idea, but it doesn't jive with the real world.
Next they'll be reporting that the English language changes too...
Re:Hey, subscriptions aren't working... (Score:5, Funny)
Try moving towards the screen really fast. It should look green then. Of course, make sure you stop before you run into the screen, because a collision with a monitor at speeds close to the speed of light might hurt.
Re:don't you see (Score:2)
we are a cancer on this planet and the sooner mother nature deals with us the better
Whether we destroy the Earth or the Sun does - it will be gone some day. The only chance that any of "mother nature's" creations have of getting off this rock is if homo sapiens carry them off. Otherwise, they're all doomed. We'll do the best we can but if we screw it up - so what? The Universe will not notice.