The Naked Scientists

The Naked Scientists Forum

Author Topic: What causes the moon's face to move in perfect synchronization with the Earth?  (Read 736 times)

Offline jerrygg38

  • Hero Member
  • *****
  • Posts: 781
  • Thanked: 27 times
    • View Profile
What causes the moon’s face to move in perfect synchronization with the Earth?
   Something causes the moon’s face to move in prefect synchronization with the Earth. It is almost as if they are geared together. As I work on studying this phenomenon, I seek some reason for this. A recent TV program about the moon specified that the Earth and moon were synchronized but gave no reason for it. In addition it said that the moon was moving away from the Earth at about 2 inches per year.
  As soon as I finish my study, I will post my answer to the synchronization problem in new theories. For the moment I would like to know if others have answers to this problem. In my opinion the answer to this question is very important because it helps to explain another property of a moving mass such as a moon within the gravitational field of the Earth.  This would also be applicable to our satellites.


 

Offline Ophiolite

  • Hero Member
  • *****
  • Posts: 716
  • Thanked: 6 times
    • View Profile
The mechanism is well understood. A good starting point is the wikipedia article:

https://en.wikipedia.org/wiki/Tidal_locking

The same mechanism is responsible for the increase in the moon's orbital distance. Note that the lock is not precise, so that over a period of time we can see more than 50% of the lunar surface.

If you think you have another explanation it will have to match or exceed, quantitatively, the current explanation in order to be treated seriously.
 

Offline jerrygg38

  • Hero Member
  • *****
  • Posts: 781
  • Thanked: 27 times
    • View Profile
The mechanism is well understood. A good starting point is the wikipedia article:

https://en.wikipedia.org/wiki/Tidal_locking

The same mechanism is responsible for the increase in the moon's orbital distance. Note that the lock is not precise, so that over a period of time we can see more than 50% of the lunar surface.

If you think you have another explanation it will have to match or exceed, quantitatively, the current explanation in order to be treated seriously.
  Thanks for the information. I gave it a quick study and it makes a lot of sense to me. It is obvious from the discussion that imperfections in the gravitational fields of the planet and moon will have particular points where the forces will be maximized. This will tend to synchronize them. thus I have nothing to add to this work. My only concern is a space-time gravitational driving force that causes a moon to rotate in synchronization with the planet. The initial rotation and the tidal forces may be much stronger than this space time force but the space time force may be important in some cases.
  Anyway I will have to think about this further. I will present this space time force on new theories. For the moment I wonder if others have additional ideas or comments.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4105
  • Thanked: 245 times
    • View Profile
The Moon is not unique. It is expected that an orbiting body close to a much larger body will tend to become tidally locked, over time.

Mercury is in an orbital resonance which is almost tidally locked to the Sun, having a day which is longer than its year.
 

Offline jerrygg38

  • Hero Member
  • *****
  • Posts: 781
  • Thanked: 27 times
    • View Profile
The Moon is not unique. It is expected that an orbiting body close to a much larger body will tend to become tidally locked, over time.

Mercury is in an orbital resonance which is almost tidally locked to the Sun, having a day which is longer than its year.
    So it appears that the locking mechanism is due to a position where the gravitational force is stronger due to non-linearities upon one face rather then nearby positions. If the moon was a perfect uniform sphere then there would be no obvious reason for it to be locked. Do you agree with that?
  Now what causes the moon to spin in the first place at birth? I believe it to be a space time force. This same force would have effects upon the electron in the Bohr orbit. This would produce another spin component which would cause variations in the light spectra. For this case the electron would be locked into different orbits due to the interactions of the spin around the proton and the spin of the electron itself. I am still thinking about this.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4105
  • Thanked: 245 times
    • View Profile
Quote from: jerrygg38
Now what causes the moon to spin in the first place at birth?
A popular theory today is that the Moon formed when a Mars-sized planet had a glancing collision with the Early Earth, throwing a large amount of molten and vaporized rock into Earth orbit, and turning the Earth into a molten mass.

A lot of the debris would have crashed back onto the Earth, but some would have remained in orbit, and over time, coalesced into a single body. This body would have had an overall angular momentum, as material in lower orbits travels faster than material in higher orbits. So the initial Moon would have been spinning.
See: https://en.wikipedia.org/wiki/Giant-impact_hypothesis

Quote
If the moon was a perfect uniform sphere then there would be no obvious reason for it to be locked. Do you agree with that?
Yes and No.... There are two issues here:
(1) A Uniform Moon will stop rotating
Just as the Moon raises tides on the spinning Earth, the Earth will raise (much larger) tides on a spinning Moon.
Raising tides involves squishing the rocks backwards and forwards, and this takes energy. This energy has to come from somewhere, and that somewhere is the rotation of the Moon. So even if the Moon were a perfect sphere, it would still slow down.

You can see this tidal energy at work on Jupiter's moon Io, where this tidal squishing produces volcanoes that erupt 500km high!

Because angular momentum is conserved, the "lost" angular momentum now appears as the slowing rotation of the Earth, and the Moon slowly drifting farther from the Earth.

2. Where it stops rotating will depend on asymmetry
The appearance of the Moon differs between the near and far sides. The near side has more basalt flows, while the far side has more mountains and cratering.

The recent GRAIL space mission mapped the Moon's gravitational field, producing detailed maps of the Moon's density, and it found some asymmetries between the two sides.

These asymmetries will influence which side of the Moon will eventually come to rest facing the Earth.
https://en.wikipedia.org/wiki/Gravitation_of_the_Moon
 

Offline VanVinci

  • First timers
  • *
  • Posts: 4
  • Thanked: 1 times
    • View Profile
...
Now what causes the moon to spin in the first place at birth? I believe it to be a space time force. ...

Being the product of Gravity, ultimately you can reach complicated explanations using Einstein's GR, but the cause is easily visualized relying solely on Newtonian ideas.

It is also fundamental to everything that has been happening in the Cosmos since fundamental particles with Mass showed up after the big bang.

So let's start with a volume of space filled with gas & dust like the Great Orion Nebula.

Until the last decade, we always assumed that this gas & dust started clumping together purely due to their tiny mutual gravitational attraction. However, a serendipitous discovery on one of the latter Shuttle missions revealed that Electrostatic charges (Static Cling) gave a massive jump start to the process of clumping dust & gas molecules.

Eventually you end up with hefty chunks scattered all about and an ever so feeble tug of mutual gravity working its magic. As huge chunks start falling towards one another they are also tugging, and being tugged by, lesser or more distant chunks that slightly alter their collision course. 

In fact, the odds that these two chunks aren't significantly influenced by additional objects is so rare that we could say it is an astronomical improbability. :p

So what does all this mean????

It means that objects of approximately the same mass rarely collide but rather brush passed each other and then lock in a spiraling dance.

How about all those other objects that tugged them from their collision course????

They are still slowly drifting inward towards the duo and are being influenced not just by the direction of the spin, but also the plane of the spin.

An embryonic accretion disk is formed.This is the source of all the rotational phenomenon we see above us. From rotating Comets hard to land a probe on to the Pinwheel of our own Galaxy.
 

Offline jerrygg38

  • Hero Member
  • *****
  • Posts: 781
  • Thanked: 27 times
    • View Profile
To evan-an and VanVinci
  Thanks for your interesting comments. Looks like things are quite complicated. One thing for sure when we have two particles things are fairly simple but once we have huge numbers of particles the complications require specialists to understand.
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums