What if the earth's rotation slowly stopped?

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silylene

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What would the earth look like if it were somehow gradually spun down to cease spinning on its axis? This thought experiment was examined in detail here: http://www.esri.com/news/arcuser/0610/nospin.html

Please click the link above, the article is long with a lot of details and a nice movie of how the earth would change as it was despun. Note that their mathematical simulations ignore geostatic rebound (which would happen and be a source of large earthquakes)...so the maps are the immediate effect in the centuries after despun, not what our planet would look liked millions of years of geostatic rebound.

Small section below:
What would happen if the earth's rotation slowed down and finally stopped spinning over a period of a few decades? ArcGIS lets us model the effects of this scenario, performing calculations and estimations and creating a series of maps showing the effects the absence of centrifugal force would have on sea level.

If earth ceased rotating about its axis but continued revolving around the sun and its axis of rotation maintained the same inclination, the length of a year would remain the same, but a day would last as long as a year. In this fictitious scenario, the sequential disappearance of centrifugal force would cause a catastrophic change in climate and disastrous geologic adjustments (expressed as devastating earthquakes) to the transforming equipotential gravitational state.

The lack of the centrifugal effect would result in the gravity of the earth being the only significant force controlling the extent of the oceans. Prominent celestial bodies such as the moon and sun would also play a role, but because of their distance from the earth, their impact on the extent of global oceans would be negligible.

If the earth's gravity alone was responsible for creating a new geography, the huge bulge of oceanic water—which is now about 8 km high at the equator—would migrate to where a stationary earth's gravity would be the strongest. This bulge is attributed to the centrifugal effect of earth's spinning with a linear speed of 1,667 km/hour at the equator. The existing equatorial water bulge also inflates the ellipsoidal shape of the globe itself.
nospin_9-lg.jpg

nospin_5-lg.jpg
 
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BurgerB75

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That's actually pretty cool. I can't imagine how messed up the climate would be with that huge landmass along the equator.

One thing though, it would be neat exploring all that dried up ocean floor. :D
 
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silylene

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I can just imagine the huge earthquakes, volcanic and plate motion that would be caused by isostatic rebound over the next 10s of millions of years. The earth would slowly revert back to a much more spherical shape. Things would get wild and wooly !

On another thought...if long long ago when Mars was warmer....if it were spinning much faster, maybe its north-polar ocean which existed way back then would not be completely lodged in the N. polar basin, but rather spread out more towards the equatorial latitudes by centrifugal forces. I wonder if the Hellas impact despun Mars to some extent?
 
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kk434

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And it won't be possible to place a geostationary satelite in orbit. Existing "geostationary" satelites would just circle the earth in 1 day orbits.
 
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bdewoody

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I would think that this scenario is highly improbable as long as the moon is with us and I'm not sure what useful data we can extract from such a thought experiment.
 
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StarRider1701

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bdewoody":3p3tabg1 said:
I would think that this scenario is highly improbable as long as the moon is with us and I'm not sure what useful data we can extract from such a thought experiment.

Agree^. Especially since not much thought was put into it. They left a very significant portion of our planetary environment completely out of the equation - ICE. No polar caps in the picture at the beginning of the slowdown. No mention of the buildup of ice on the dark side as the Earth completed its one year long day once the Earth stopped spinning. I did not read every word, but also didn't notice any mention of the effects of oceans freezing and melting during the slowdown process. The entire process seemed to start with all the world's ice being liquid water and remaining liquid water during the process. Totally and completely unrealistic.
 
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orienteer

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Why would there be a one year long day? The moon has a 1 to 1 ratio because it is revolving around the earth, but if earth were tidally locked to the sun then there should be a day side and a night side, with lots of ice on the night and desert on the day.
 
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planetling

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bdewoody":345frcpe said:
I would think that this scenario is highly improbable as long as the moon is with us and I'm not sure what useful data we can extract from such a thought experiment.

Apollo 11 set up a laser reflector on the moon to measure its distance from the Earth. Over periods of time it was calculated that the moon is in fact escaping Earth at about 4 cm per year. In other words, the moon is falling up!

Lots of interesting data came from this, such as how the moon might have appeared from Earth long, long ago. What a sight that must have been!

So, for another thought experiment, someday the moon may not be with us anymore :cry:
 
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MeteorWayne

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Actually, the moon will always be with the earth; it will just get further away until the sun expires...after that, anything can happen depending on the mass loss rate of the sun, and whether we are absorbed by the sun, or have moved far enough away by then (> 5 billion years)
 
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planetling

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MeteorWayne":qd04b38g said:
Actually, the moon will always be with the earth; it will just get further away until the sun expires...after that, anything can happen depending on the mass loss rate of the sun, and whether we are absorbed by the sun, or have moved far enough away by then (> 5 billion years)

I may be incorrect, so maybe somebody can help:

but the further an object is from another object, gravity weakens. The current rate of 4 cm per year would INCREASE as the moon gets further away from Earth. Over time, that 4 cm number would keep growing to larger numbers at an even faster rate. Eventually gravity would be so weak between Earth and the moon that the suns gravitational force would pull the moon completely out of Earth orbit. Whether that happens before the sun expires or some other catastophic event is something to consider, I would imagine.

Has anybody run the numbers for this scenario?
 
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MeteorWayne

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That's not the situation. The moon is firmly in the grasp of the earth's gravity. The outward motion is due to tides transferring momentum from the earth to the moon. The earth's rotation rate slows down, and the moon moves outward. If our earth-moon system survives the red giant phase of the sun, eventually the earth and moon will both become tidally locked to each other (IOW, the moon will always be over the same point on the earth; the other side will never see it), and at that point the moon will stop moving outward.

MW
 
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StarRider1701

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orienteer":mvxv3n14 said:
Why would there be a one year long day? The moon has a 1 to 1 ratio because it is revolving around the earth, but if earth were tidally locked to the sun then there should be a day side and a night side, with lots of ice on the night and desert on the day.

But the OP didn't say, "What if the Earth became tidally locked?" It said what if the Earth's rotation STOPPED. With no rotation at all, then a day would be half a year long and a night would also at any given point on the planet. Because the Earth is still going around the Sun, it just stopped spinning on it's axis. Of course this would be at the end of the cycle, after the rotation stopped.

Needless to say, this would kill pretty much all life on the planet. Certainly all large, complex life. Maybe a few tube worms might still live at the bottom, clinging to vents in the ocean floor. As well as anything that can adapt to living in the deep ocean trenches that won't freeze. I'm guessing that enough meltwater from constantly thawing ice will keep the oceans cool enough during the half a year long day to keep them from evaporating. Although I'm guessing that, in the long run the Sun will win that battle.
 
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orienteer

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StarRider1701":1pe9wqms said:
orienteer":1pe9wqms said:
Why would there be a one year long day? The moon has a 1 to 1 ratio because it is revolving around the earth, but if earth were tidally locked to the sun then there should be a day side and a night side, with lots of ice on the night and desert on the day.

But the OP didn't say, "What if the Earth became tidally locked?" It said what if the Earth's rotation STOPPED. With no rotation at all, then a day would be half a year long and a night would also at any given point on the planet. Because the Earth is still going around the Sun, it just stopped spinning on it's axis. Of course this would be at the end of the cycle, after the rotation stopped.

Needless to say, this would kill pretty much all life on the planet. Certainly all large, complex life. Maybe a few tube worms might still live at the bottom, clinging to vents in the ocean floor. As well as anything that can adapt to living in the deep ocean trenches that won't freeze. I'm guessing that enough melt water from constantly thawing ice will keep the oceans cool enough during the half a year long day to keep them from evaporating. Although I'm guessing that, in the long run the Sun will win that battle.


Can you give any examples of a non-rotating moon or planet? I don't think Einstein allows it.
 
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orienteer

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MeteorWayne":3kpsj8by said:
Why would Einstein have anything to do with it?

To not be tidally locked at such a slow speed, I would expect to find a perfectly centered mass. As soon as one side is a little denser, it should gravitate towards the parent body.
 
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csmyth3025

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Although this is somewhat off-topic, I wonder if there have been any conjectures made about the effects of the Earth's axis of rotation being oriented in line with the plane of the solar system as is the planet Uranus.

Without speculating on the improbability of a collision strong enough to alter the Earth's rotation by an additional 77 degrees leaving the Earth intact, I do wonder if such a change in axial tilt would have made a significant difference in the ability of life to evolve on the planet. In this regard I'm thinking of the currently accepted moon-forming encounter with the protoplanet Theia.

Wikipedia has this to say about such an axial orientation:

If Earth's axis of rotation were to approach the plane of the ecliptic, extremely severe weather could result from the resulting extreme seasonal differences. One pole would be pointed directly toward the Sun during summer and directly away during winter. Planetary scientists who have studied the effect claim that this might kill all large animal and higher plant life

I wonder if these planetary scientists underestimate the potential for "large animal and higher plant life" to evolve and adapt to such a bizarre (to us) climate. An example that comes to mind are the wood frogs that can seemingly be frozen solid and revive after thawing out.

Chris
 
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MeteorWayne

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I'm sure once life formed it would adapt, but a wood frog ain't a human; the energy requirements are vastly different.
 
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csmyth3025

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MeteorWayne":37m0h9cn said:
I'm sure once life formed it would adapt, but a wood frog ain't a human; the energy requirements are vastly different.

I have to admit that it was a pretty lame example.

Chris
 
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silylene

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csmyth3025":2pukn3ai said:
Although this is somewhat off-topic, I wonder if there have been any conjectures made about the effects of the Earth's axis of rotation being oriented in line with the plane of the solar system as is the planet Uranus.
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If Earth's axis of rotation were to approach the plane of the ecliptic, extremely severe weather could result from the resulting extreme seasonal differences. One pole would be pointed directly toward the Sun during summer and directly away during winter. Planetary scientists who have studied the effect claim that this might kill all large animal and higher plant life

I wonder if these planetary scientists underestimate the potential for "large animal and higher plant life" to evolve and adapt to such a bizarre (to us) climate. An example that comes to mind are the wood frogs that can seemingly be frozen solid and revive after thawing out.

Chris

I think the farside pole and hemisphere winter would grow an *enormous* glacier / icecap. The collection of so much water on the farside pole would deplete the amount of water available on the nearside summer hemisphere, causing large shifts in water level. Temperatures would be much colder, and CO2 would even precipitate.

As the earth rotated around the 180 degrees around sun, the iceaps and glaciers would melt and transfer to the other polar region, and the sunside polar region would become positively balmy and then roasting hot. During the summer and winter, the equitorial regions would get quite cold, it would be like winter just above the Arctic circle in terms of illumination.

In summary, the polar regions would alternate from far too cold and too hot, and the equitorial regions would experience a climate swings from tropical to Icelandic.

Life would be possible, just harsh.
 
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adrenalynn

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MeteorWayne":3jlyd63g said:
Why would Einstein have anything to do with it?

He was feeling feisty that day... [sorry, had to say it]
 
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csmyth3025

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silylene":1kobcf05 said:
...In summary, the polar regions would alternate from far too cold and too hot, and the equitorial regions would experience a climate swings from tropical to Icelandic.

Life would be possible, just harsh.

I agree that most larger life forms would tend to congregate in the tropical and sub-tropical regions, with larger animals migrating poleward and then back as the seasons change semi-annually. Plants and smaller animals not doing so would probably develop some sort of hybernation strategy.

Maybe if there are a bunch of climatology post-grads sitting around bored out of their skulls, they'll steal some idle time on a supercomputer and plug in a 90 degree axial tilt for the Earth just for the fun of it. The results would be interesting.

Chris
 
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StarRider1701

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orienteer":2kijuzii said:
StarRider1701":2kijuzii said:
orienteer":2kijuzii said:
Why would there be a one year long day? The moon has a 1 to 1 ratio because it is revolving around the earth, but if earth were tidally locked to the sun then there should be a day side and a night side, with lots of ice on the night and desert on the day.

But the OP didn't say, "What if the Earth became tidally locked?" It said what if the Earth's rotation STOPPED. With no rotation at all, then a day would be half a year long and a night would also at any given point on the planet. Because the Earth is still going around the Sun, it just stopped spinning on it's axis. Of course this would be at the end of the cycle, after the rotation stopped.
Can you give any examples of a non-rotating moon or planet? I don't think Einstein allows it.

This has nothing to do with either Einstein or reality. This is a "what if" thought game, and I was actually pointing out that by leaving ice totally out of thier game, they hadn't put as much thought into the game as they thought! :roll:
 
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