Poser for the physicists!

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Trevor
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Poser for the physicists!

Post by Trevor »

Poser for the physicists; Is the moon's axial rotation tidally locked or locked by virtue of magnetic inductive repulsion from the earth's magnetic poles.
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re: Poser for the physicists!

Post by Jim Williams »

Just because I'm too lazy to look it up, and if we last so long, does Earth itself first tidal lock with the moon or with the sun?

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Last edited by Jim Williams on Thu Feb 23, 2017 4:42 pm, edited 1 time in total.
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re: Poser for the physicists!

Post by Trevor »

That is now a whole nother can of worms; I am specifically talking about the moons axial synchronisation with the earth.
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re: Poser for the physicists!

Post by Jim Williams »

Probably just to confuse the issue, how does Mercury lock with the sun?

Could the moon lock with Earth because of both a tidal lock and magnetic inductive repulsion together? Or would one dominate the other?
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Post by Furcurequs »

Jim Williams wrote:Just because I'm too lazy to look it up, and if we last so long, does Earth itself first tidal lock with the moon or with the sun?

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Hey Jim,

I hadn't considered the earth tidally locking with the sun before, so I decided to look it up. I found a physics forum discussion here:

https://www.physicsforums.com/threads/w ... ed.523463/

Someone in that forum thread said the earth would tidally lock with the moon first and then calculated that it would take the earth 5.5 times longer to lock with the sun than to lock with the moon.

I'm not familiar enough with the problem to be able to check the math. It seems to me that the moon being in orbit around the earth might have an effect that would need to also be considered in the calculations for the tidal locking to the sun.

Anyway, it's interesting to think about.

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re: Poser for the physicists!

Post by Jim Williams »

Dwayne:

I forgot the moon is moving away from Earth, but now I see the sun would take over at some point. I'll assume for me the 5.5 times is correct since I'm not only unfamiliar with the problem, but with the math, too.

I'd think there would always be a rocking movement with the moon also continuing to pull on Earth with the sun. I have no idea if that would all influence the 5.5 times it takes for the sun to take over for the moon.

My guess is that the sun becoming a red giant expanding to the orbit of Mars in 6 billion years will happen before the sun takes over anything.

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re: Poser for the physicists!

Post by Trevor »

I feel that the axial locking of the moon to the earth is far more likely to be due to the latter; magnetic inductive repulsion.
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re: Poser for the physicists!

Post by Jim Williams »

Trevor:

Sort of like this? Is this related? I really don't see it.

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http://www.patentsencyclopedia.com/imgf ... 0311775_01
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re: Poser for the physicists!

Post by Trevor »

Interesting Jim, but if the moons core is in anyway conductive it will always ultimately axially find a position of rest at right angles to the magnetic flux of the earth.
Even if the moon had been rotating originally it would eventually slow down in synchronisation with its orbit.
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Post by charly2 »

I think the tidal lock is more a physical deformation, this happens to most of moons with a near orbit relative to their host planet enough to deform the moon like an egg shape. This comes from ther earlier stages in the solar systems creation.
Gravitational force pulls the moon inward and centrifugal force outward, this is the cause of the deformation.
Far orbit moons have less gravitational force and lower orbit speed thus less centrifugal force too, so less deformation and is possible to have their own independant rotation.
The two forces change at different ratio along to the orbit radius. So it is not easy for the moon overcomes this state.
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re: Poser for the physicists!

Post by Trevor »

chary 2, I find that hard to accept because the advancing deformation would be nulled by the receding deformation.
If that happened then the earth's axial rotation would have long time done the same with the sun's greater gravity and the tides of the earth also being much greater.
They use an argument that the earth is slowing down!... but I really think that is because 50,000 tons of light is falling on the earth every year, not to mention the cosmic ray bombardment.
This would definitely have the affect of slowing the earth down.
Remember, every body in space, no matter how deformed, always revolves around it's center of gravity.
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Post by charly2 »

Usually if any body will tend to rotate it will do it around its center of gravity. But things get complicated when has to rotate and translate around a center at the same time, new forces play in the object in question.
I just have found this explanation after your post Trevor:
https://en.wikipedia.org/wiki/Tidal_locking
I think it is related in certain way to the Bessler´s secret quest. Why some moons rotate and others not?
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re: Poser for the physicists!

Post by Trevor »

Okay thanks charly2, it will take quite a bit of study to evaluate this because I want be clear in my own mind.
As I said I don't believe tidal locking is credible because it's not evident between the earth and sun.
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re: Poser for the physicists!

Post by Trevor Lyn Whatford »

Hi Trevor,

the Moon has had many collisions with large objects of different mass density. I therefor think the Moon is no longer balanced (if indeed it ever was) so the heavier part of the Moon is always pointing to the Earths Center of Gravity, just like adding a weight to a wheel the weight will rotate until it finds the strongest gravitational pull (the bottom).

The Moons Orbit and facing, seems to me too be more in step with Gravity than magnetism, I would think Magnetism is playing its part though, but its not the main player in the scale of things.
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re: Poser for the physicists!

Post by Trevor »

Trevor, I used to think it was gravity at first but then I realized that every body, what ever the shape, always revolves on its center of gravity so it always presents the same mass towards earth.
That is why I just had to choose the magnetic theory.
Another reason why I also discounted tidal locking is because there are some moons that revolve and some that don't.
Last edited by Trevor on Tue Feb 28, 2017 2:31 pm, edited 1 time in total.
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