Could the Earth ever stop spinning, and what would happen if it did?

rod

Oct 22, 2019
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Some thoughts here. The article says, "The Earth has been spinning since its birth, four and a half billion years ago. The Earth was made from rubble that was left over when the sun formed from the collapse of a huge cloud of matter. The rubble that went on to become the Earth circled around the sun like water does around the plughole when you empty a bathtub, spinning as it went. The Earth continued to circle the sun and spin after it was formed and is going to spin like this for a long while to come."

Question. What was the original length of day (LOD) of the primitive or proto-earth?

The article says, "If the Earth stopped spinning, you wouldn't suddenly be launched off into space. Gravity would still keep you firmly on the ground."

Question. What about conservation of angular momentum and any violent reactions here? :)

The article stated, "If the Earth didn't spin, the night sky would always show the same constellations of stars, because you would always be looking out into space in the same direction. This is very different from seeing the stars rise and set during the night, and seeing different constellations at different times of the year."

Question. Is this true? Consider the geocentric Earth or heliocentric Earth model.
 
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Wolfshadw

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Question. What was the original length of day (LOD) of the primitive or proto-earth?
Not sure anyone knows. If I remember correctly, the Earth had a rotation period of around 14 hours once the Moon formed and it's been slowing ever since, but before the Moon formed; not sure how that might be calculated.

Question. What about conservation of angular momentum and any violent reactions here?
If the Earth came to a sudden halt, then yes, we'd all have a really bad day, but if the Earth's rotation gradually slowed, then I don't think there's be much angular momentum to worry about.

Question. Is this true? Consider the geocentric Earth or heliocentric Earth model.
Yes, this would be accurate. If the Earth stopped rotating, then the same side of the Earth would continuously be facing the same direction. I think you might be thinking Tidal Lock as opposed to a complete stop of rotation.

Just my simple understanding of things.

-Wolf sends
 
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rod

Oct 22, 2019
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Wolfshadw, some good answers :) Concerning the early earth rotation, perhaps 3-5 hour day now in the giant impact model using Theia. Concerning the Earth slowing down - suddenly, yes big problems :) George Darwin with the fission model for the origin of the Moon had an Earth spinning near 2 hour day.

I used MS BING search and found this about seeing different constellations at different times of the year.

"We see constellations at different times of the year - spring, summer, fall, & winter. This occurs because the Earth is orbiting the Sun. In winter, we see the constellation Orion in the south at night and during the day the Sun is in the sky with the constellation Scorpius."

Copernicus understood this with a spinning Earth revolving around the Sun. The geocentric astronomy said the stars and constellations moved around the Earth that was immovable. If the Earth was not spinning on its axis, the night side would eventually see different star patterns at night, so long as the Earth continued to revolve around the Sun. If the Earth did not spin on its axis, the day side would always face the Sun and the night side in the dark or shadow of the planet. Weather patterns and temperatures would be very different across the Earth :)
 
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Wolfshadw

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George Darwin with the fission model for the origin of the Moon had an Earth spinning near 2 hour day.
Did not know that. Thanks for sharing! :)

I used MS BING search and found this about seeing different constellations at different times of the year.
Technically, yes. That is accurate, but only from the stand point at one day/night cycle takes an entire year. Obviously, you don't see constellations at high-noon, but six months later, when you're part of the planet is facing away from the Sun, you will see the same constellations that you saw the year before. If the Sun suddenly blinked out during high-noon, you'd see the same constellations as you would at midnight

If the Earth did not spin on its axis, the day side would always face the Sun and the night side in the dark or shadow of the planet.
Not correct. This is called tidal lock and the Earth's rotation is matched by it's orbit around the Sun. One Earth rotation equals one orbital period around the Sun, but the Earth is still rotating (albeit very slowly).

-Wolf sends
 
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Nice discussion!

The article says, "If the Earth stopped spinning, you wouldn't suddenly be launched off into space. Gravity would still keep you firmly on the ground."

Question. What about conservation of angular momentum and any violent reactions here? :)
The "firmly" part should not imply loose objects wouldn't go flying at the instant the Earth stopped rotating, just as things go flying in a car wreck. The speed they would instanly have would be about 1100 mph * cos( your lattiude). But, this speed isn't fast enough to become untethered to the Earth.

The energy necessary to actually stop the Earth must eqaul or exceed that angular momentum energy. This energy, however, might be used to alter spacetime to cause a gentle stop, even if very quick. From GR we know that how things (masses) move is tied directly to the shape of spacetime. Suddenly alter spacetime and things move suddenly differently.

Frame-dragging is the term used that describes how a rotating body drags spacetime with it. [ It was first measured, IIRC, by Gravity Probe B. ] What if you could, with your magic wand, dramatically force spacetime to be dragged in the opposite direction? The new "path of motion" would suddenly be altered and things, firm or loose, would not experience any flinging... maybe?

It would take, however, someone very knowledgeable about GR to answer this question, but I think it is a fair question.

Question. Is this true? Consider the geocentric Earth or heliocentric Earth model.
Adding to what Wolf stated, the non-rotation is meant to be relative to the fixed stars, not the Sun. Just like there is no seasonal change, or much of one, with Polaris. There would be only half a year where the night sky would be visible, and the Sun would fill the other half.

George Darwin was the first to explain tides. He offered his hypothesis of the Moon moving away from the Earth due to the tidal effects. His 2 hour rotation rate was based on a speed that would allow material from Earth to spin off the Earth, which was his idea about how the Moon may have formed.

The modern figure is abut 5 hours per day. This is by reversing the clock and having the Moon move close enough to the Roche limit.

The impact that formed the Moon would have greatly altered the Earth's rotation speed, so any guess as to its orginal speed may be wild. Perhaps exoplanet rotation rates, once determined, may help give us a better idea.
 
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Wolfshadw

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What if you could, with your magic wand, dramatically force spacetime to be dragged in the opposite direction? The new "path of motion" would suddenly be altered and things, firm or loose, would not experience any flinging... maybe?
All we need is Superman! :)

And to expand on what @Helio states, the Moon if tidally locked with Earth. It's rate of revolution is the same as it's orbital period around Earth. If you could stand on the far side of the moon (almost said Dark side), you would never see the Earth, but you'd still see the seasonal constellations as if you were on Earth.

-Wolf sends
 
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rod

Oct 22, 2019
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Just to clarify folks, the article does not mention the Earth as tidal locked but *stopped spinning*. This means Earth has zero angular momentum and does not rotate on an axis. Tidal locked planets and moons (like our Moon) do have angular momentum and can be very slow spin, but still some spin :)
 
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All we need is Superman! :)

And to expand on what @Helio states, the Moon if tidally locked with Earth. It's rate of revolution is the same as it's orbital period around Earth. If you could stand on the far side of the moon (almost said Dark side), you would never see the Earth, but you'd still see the seasonal constellations as if you were on Earth.

-Wolf sends
So, how many Superman orbits are required due to stop the Earth's rotation due to tidal drag? :D I also noticed that his orbital inclination was perturbed. I suppose this was due to the Moon's orbital inclination.
 
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Just to clarify folks, the article does not mention the Earth as tidal locked but *stopped spinning*.
This raises the question of what not spinning means since it must be considered as "stopped spinning" relative to what.? Your correct if they mean relative to the Sun, but I suspect the refernce is meant to be relative to the stars (siderial rotation time = 0).
 
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rod

Oct 22, 2019
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This raises the question of what not spinning means since it must be considered as "stopped spinning" relative to what.? Your correct if they mean relative to the Sun, but I suspect the refernce is meant to be relative to the stars (siderial rotation time = 0).
Helio, some deep thinkers in these posts :) However, note the source of the question. "Could the Earth stop spinning, and if it did, what would happen? – Paul, aged 12, Aberdeen, Scotland"

Perhaps some in these posts are thinking to hard about the answer(s) :)
 
Jun 1, 2020
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Helio, some deep thinkers in these posts :) However, note the source of the question. "Could the Earth stop spinning, and if it did, what would happen? – Paul, aged 12, Aberdeen, Scotland"

Perhaps some in these posts are thinking to hard about the answer(s) :)
:) Ok, but I too will discover that my questions included ambiguity. ;)
 
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