Earth "getting fatter"

BBC ^ | August 2, 2002 | BBC

[Damocles]

Earth 'getting fatter'

The changes are very, very slight

Scientists have known for some time that the Earth is not a perfect sphere.

It is shaped a little like a pumpkin - wider at the middle and narrower at the poles. It is difference of more than 20 kilometres.

But now new research published in the journal Science suggests our planet is getting even wider - if only by the odd millimetre.

The scientists behind the report, Christopher Cox and Benjamin Chao, base their findings on space-based observations from past 25 years.

Abrupt change

Since the early 1980s, satellite laser-ranging studies that have been used to work out the planet's gravity field have demonstrated how the Earth has lost a bit of its pumpkin look - it has actually become slightly more spherical.

This has been put down to a rebound effect in the mantle - a thick layer of nearly molten rock between the Earth's crust and its core - following the loss of the heavy mass of ice at the poles after the last Ice Age.

But Cox and Chao say their work suggests this trend was reversed abruptly from about four years ago.

They are doubtful that phenomena such as further glacial melting or atmospheric changes can explain the rapid turnabout.

Small measurement

Instead, they suggest two possibilities. One is that changes in ocean circulation have shifted a larger mass over water towards equatorial regions; the other is that there has been a shift in mass at the boundary between the Earth's fluid outer core and the mantle.

Further studies will be required to work out what is really happening.

Cox says any increase in the Earth's girth is of the order of millimetres and may even be imperceptible given the rather technical way these things are monitored.

"It depends on where the effect is, because it is measured in terms of a change in the shape of the gravity field," he says.

"If it is in the ocean, it may be a few millimetres, but if it is in the core there could be no apparent change in the actual shape of the Earth."

 

[Damocles]

This is obviously the fault of "big fat". Expecting the next lawsuit to be filed post haste.

[6ppc]

We're being Nadlerized!

[Wolfie]

What I hate is when Summer rolls around, and the Earth tries to squeeze into spandex shorts and a halter top.

[JediGirl]

bump

[Blackdakota]

Oh No!! Now Earth is becoming obese. Between that and Second hand smoke, The Earth is toast!

[Eric in the Ozarks]

Someone put in a call to Algore.

[Michael_S]

Maybe that's why it's so hot in the North East USA. We're a millimeter closer to the Sun.

For those of you who do not know, in this forum that's probably very few, a millimeter is about the thickness of a dime.

[GodBlessRonaldReagan]

What I hate is when Summer rolls around, and the Earth tries to squeeze into spandex shorts and a halter top.

ROTFLMAO!

[fporretto]

Calm down, please. It's not "Big Fat." It's the constant and unrelenting pressure from the wing nuts, easily observed on any model globe!

Freedom, Wealth, and Peace,
Francis W. Porretto
Visit The Palace Of Reason: http://palaceofreason.com

[Lil'freeper]

I'm sure the UN and assorted enviro groups will find some way to blame this on America and start pressuring us into signing a treaty to make it stop.

[martin_fierro]

What I hate is when Summer rolls around, and the Earth tries to squeeze into spandex shorts and a halter top.

New Jersey = one of the stretch marks. <|:)~

[right]

I'm getting fatter around the middle too, so where's the story :~)

[Eric in the Ozarks]

Ask a Liberal...they'll tell you you're having to damn much fun and you need to stop it.

[Scully]

I'm not a geophysicist, but it would seem to me that we would see other effects such as increased continental drift, earthquakes, etc. if the interior of the earth was experiencing a shift in mass. Perhaps someone smarter than I would care to comment?

[Eric in the Ozarks]

Not suggesting any special gift, but perhaps we see the same syndrome on a potter's wheel.

[Publius6961]

and may even be imperceptible given the rather technical way these things are monitored.

Imperceptible or flat out wrong.
Knowing the mechanics of the measuring processes, "a few milimeters" can easily be noise or inherent uncertainty in the process.

[Damocles]

What I hate is when Summer rolls around, and the Earth tries to squeeze into spandex shorts and a halter top.

New Jersey = one of the stretch marks. <|:)~

Spewed my coffee on that one!!

[MissAmericanPie]

Is it getting fatter or flatter? Maybe the world really was flat at one time, hehehehe. Now I wonder if it will begin to wobble like a frisby losing momentum.

[PatrickHenry]

I'm surprised to find you freeping right now. Your dedication to this website is admirable.

[aimhigh]

Now I wonder if it will begin to wobble like a frisby losing momentum.

Actually, this is a good question. The spinning of the earth has the effect of making the middle spread out. That spread affects the spin, and it's logical to assume there is a repeating fluctuation in the speed and spread over time.

[Scully]

perhaps we see the same syndrome on a potter's wheel.

An excellent observation. Indeed it is true that celestial bodies which rotate as they accrete become almost spherical - a little fatter in the middle, but essentially they become spheres.

[Scully]

Is it getting fatter or flatter?

LOL, I was wondering if anyone would bring this up. Some smart person might well be able to tell us how short our days might actually be if the earth rotated fast enough to become a flattened disk.

[RightWhale]

It would have to be a high-order effect. Daily motion of earth's surface from tides is a lot more than this slow flattening. Any changes in local radius or curvature from a change in rate of rotation would be dampened immediately, except for a resonant frequency such as the Helmholz frequency. an interesting idea, though, that earth may sometimes get flatter, and sometimes rounder, on a regular schedule measured in years or longer.

[Gumlegs]

It's just that #%*& Body Mass Index. Doesn't distinguish between water and rock.

[VadeRetro]

Earth 'getting fatter'

At least it isn't just me!

[xJones]

But now new research published in the journal Science suggests our planet is getting even wider - if only by the odd millimetre.

Michael_S: ..., a millimeter is about the thickness of a dime.

Wouldn't it be wonderful if we could all measure our middle-age expansions in odd millimeters?

[PatrickHenry]

Some smart person might well be able to tell us how short our days might actually be if the earth rotated fast enough to become a flattened disk.

The calculations are a bit beyond me, but my guess is that the speed of rotation would need to be enormous. The crust of the earth would probably shatter. Volcanoes, obviously. The rim might be spinning so rapidly that you could launch a satellite with a bow and arrow. It would be neat if the spin were so rapid that there were observable relativistic effects at the rim (clocks would run slower at the edge, etc.).

[longshadow]

Some smart person might well be able to tell us how short our days might actually be if the earth rotated fast enough to become a flattened disk.

Assuming no energy was added (and somehow the Earth magically became a flattened disk), Conservation of Angular Momentum would require the time for a rotation to be longer than it is now, since if the entire mass of the Earth were in a flattened disk, more of it would be further away from the axis of rotation than it is presently. This is the opposite of a figure skater spinning around and pulling IN their arms, thus causing the rate of rotation to go up. This would be like a spinning skater with there arms against their body their arms; thus they would slow down in order to conserve angular momentum.

At least, that's how it seems to me.... maybe RA will weigh in on this.

[METARZAN]

Come on ladies, debunk their argument and tell them that the earth is just "big-boned".

Metarzan

[RadioAstronomer]

I wrote in one of my posts a few months ago that the earth was slowly changing from an oblate spheroid to a more spherical shape. Heck this has been known for a long time.

BTW You are correct on the rotational speed change :-)

[PatrickHenry]

BTW You are correct on the rotational speed change

Curses! I'm wrong again. (I was thinking of how fast the earth would need to spin in order to flatten itself, which is a different issue. Maybe.)

[lexington minuteman 1775]

I suspect McDonalds is to blame. And what did GW know and when did he know it?

[SamAdams76]

In a related story, the Sun has doubled the Earth's fare for moving through it's orbit. Seems Venus and Mars are bitching about having to orbit next to this fat pig of a planet.

[longshadow]

Curses! I'm wrong again. (I was thinking of how fast the earth would need to spin in order to flatten itself, which is a different issue. Maybe.)

That WAS the original question, and obviously you would need to spin the snot out of it to flatten it (but it would probably break up first).

My comments were about what would happen if the earth were to spontaneously deform into a disk, which is a "horse of a different color".....

[El Gato]

Knowing the mechanics of the measuring processes, "a few milimeters" can easily be noise or inherent uncertainty in the process

I'm sure the folks makeing the measurements know about the mechanics and uncertainties too. With a history of measurements, showing a reversal of a long established trend, you can pretty much discount most of the measurement errors, and most of the inherent uncertainties too. Even if the earth isn't getting bigger around the equator, something is changing, and change is always interesting.