Why Is The Moon Not Spinning Then?

Discussion in 'Pseudoscience Archive' started by common_sense_seeker, Sep 6, 2008.

  1. Robittybob1 Banned Banned

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    There will come a time both the Earth and the Moon stop spinning and there will no more tides.
    But if the Moon was still spinning the orbit of the Earth would show a greater eccentricity, I believe.
     
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    So you do not believe angular momentum is always conserved.
    Have any reason for that false belief?
     
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  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    No The moon is spinning about it axis with the same period as it rotates about the Earth (27.3 days) This is due to Phase Locking, not moon now lacking an internal engine- read more of my post.

    The gravitational torques on a small body are less than same gravitational gradient acting on a larger body.

    Thus the torque of the moon´s gravitational gradient acting on the Earth´s core is less than upon the outer shell. The nature of this torque is to slow the rotation of the Earth. (Days are getting longer and until it became too much trouble for some computer systems and GPS´s highly accurate clocks, a "leap second" was added every few years to the current year to keep the 360 degree rotation be exactly one clock day.) Thus with stronger torque on the shell, the shell has slowed it rotation down more than the core has. - there is no "internal engine".

    1000 and more year old Chinese records of which cities experienced total eclipse record them farther to the West than they would have been observed if the Earth´s spin were same back then as the current slower rate. - It was not so in 24 hours, the faster spin back then carried the more western cities eastward into the total eclipse spot. This is how we know with high precision the average rate (over thousands of years) that the Earth´s spin has been slowing due to tidal dissipation. (There are tiny tides in the solid earth and in the moon, but almost all the dissipated energy is heating the oceans.) I.e. the angular momentum of the Earth is decreasing with time.

    Yet total angular momentum of the Earth/moon system much be conserved. This is achieved by slowly increasing the separation between the Earth and moon.

    Currently the moon´s rotation/ spin about it axis is "phase locked" to its orbital period (A more technical way to say moon always shows the same side towards the earth.) Several other planet´s moons are also phase locked to their planet. Even Venus may be phase locked to the sun ("The rotation period of Venus may represent an equilibrium state between tidal locking to the Sun's gravitation, which tends to slow rotation, and an atmospheric tide created by solar heating of the thick Venusian atmosphere.") - From: http://en.wikipedia.org/wiki/Venus#Orbit_and_rotation but it does not always show same face to the sun.

    Phase locking need not be 1 to 1 but can be 3 to 2, etc. relationships between orbital and spin periods. "Mercury has a 3:2 spin–orbit resonance, rotating three times for every two revolutions around the Sun." From: http://en.wikipedia.org/wiki/Tidal_locking

    This wiki ref has nice illustration of how phase locking is achieve by the gravity torques:

    Please Register or Log in to view the hidden image!


    Here is a little help for the those not understand this drawing:

    The green oval is an exaggerated showing that the orbiting moon has "mass bump" - is not a sphere. As it orbits around the central black mass, if it is spinning too fast (not yet phase locked) it would be with the orientation shown in red. But as you can see, the red orientation would give rise to a torque trying to twist it into the green position. i.e. slow its spin down, so during one fourth of the orbit, it has rotated about it axis 90 degrees too.

    Once it is spinning with the same period as the orbit, the green positions, then it is phase locked 1 to 1 like the moon is. I.e. will always keep the same side towards the black mass.

    If any planet´s moon is keeping same side to its planet, then it is in 1 to1 phase lock. I.e. that moon´s period of its spin about its axis is the same as its orbital period. Earth´s moon is but one of several in 1 to 1 phase locked condition.

    It is sad so much false and unfounded speculation is posted here when the truth is easily discovered, even just at Wiki, but I admit many do not already know a set of terms like "phase locked" to search with.
     
    Last edited by a moderator: May 13, 2012
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  7. sadang Registered Member

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    Billy, if you had read my post carefully, you would not irritates so easily. I said "I consider that this is ..." I have not said "this means". It was just a subjective opinion! Or should I not own opinions, but instead only approve your "FACTS"? Perhaps a little modesty would not hurt you!

    Following your path of thinking, and of course your math, and making a forced statement accordingly, "I, for certainly affirm that our Moon is not orbiting around the Earth at all! Instead it real orbiting path is around our galactic center, and its tiny oscillatory crossing of the Earth's trajectory around the Sun, and of the Sun trajectory around the galactic center, give only a FALSE impression that the Moon is orbiting the Earth and the Sun!" What do you think about this? It is a normal extrapolation, complying the rules of your way of thinking, and your math. Do you agree with my statement? Or not?

    As I already said in a previous message, try to adapt your math to real movement of the Sun-Earth-Moon system, not the real movement of this system to your math. And try to not forget, that image from wikipedia is just a projection on a sheet of paper, a draw which represent the both paths followed by Earth and Moon on their revolution around the Sun, over a period of time. This image do not represent the true motion, but the graphical representation of the vectorial summation of the angular momentum of the Moon and Earth wrt the Sun, over a period of time covering a full revolution of the Moon around the Earth (~27 days).

    The real movement of this system can be seen here (real movement wrt the Sun):
    - h t t p://phys23p.sl.psu.edu/phys_anim/astro/embederQ4.15100.html

    And here can be seen something similar to that image from wikipedia (projection pats wrt the Sun):
    - h t t p://phys23p.sl.psu.edu/phys_anim/astro/embederQ4.15200.html

    To see these animations you need to have installed the QuickTime player!

    Which one do you think that represent the real movement of the Earth-Moon system around the Sun? The first one, or the second one?

    Your example with the car around the train is a false example, due to the next:
    - both the car an the train are two separate and independently acting objects
    - both have their own independent energy of motion (kinetic energy)
    - if both object have the same independent velocity (wrt the Sun) they never can cross the path of the other, back and fort (or up and down depending on the reference point of view) - lack of monthly phases
    - both the train and the car are moving independently on a straight path, they do not orbit around a center of rotation

    No, I am not so SILLY to describe the car movement as orbiting the train. But also, I am not so SILLY to accept your totally false analogy of the train and car movement with the Earth and Moon movement. And one more thing: to make 100 feet on both sides of the train the car must have to accelerate or decelerate, and to change its velocity. And of course it can do this, because it has a movement independent from the train. Do you think the Moon has something similar, or can do something similar?

    And wrt to your last message, the apology of the Moon synchronous spin with revolution movements, explain how, in the case when the Moon has its own axial rotation, even a single REAL rotation during a revolution, if I am on the unseen side of the Moon, why I can not still see the Earth?
     
  8. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    First they are not "my facts" or even "my opinions."

    You (and I) should not have contrary opinions about facts that are well accepted by the scientific community, such as (1) lead is denser than copper OR (2) moon only makes very tiny wobbles from it other wise perfect ellipse about the sun due to slight perturbation forces of the Earth (The max deflection of that wobble from the perfect ellipse, occurring at full moon, is less than 1/4 of one percent of moon´s distance from the sun.).

    These facts about moon´s motion were published in 1912 in a pier-reviewed and very respected astrophysical journal and recently re-confirmed by NASA´s republishing that same article as part of its educational program.

    But I have a well supported (by your replies) opinion that you prefer to remain ignorant and hold fast to opinions contradicted by well establish scientific facts.

    Perhaps you hold the opinion that copper is denser than lead too? If not, why not? - You seem to feel free to select which scientific facts you should hold contrary opinions too?

    -------------
    Yes it is true the sun/ solar system/ is "orbiting the galactic center" but in one year Earth & moon orbit 360 degrees around the sun in essentially a perfect ellipse.

    In that same time the angular progress of solar system about the galactic center is only 360 / 200,000,000 degrees as the full orbit would take 200 million years. It not unlikely that there would not be some serious scattering by "near misses" (dozens of light years miss) with other much more massive solar systems so even calling it an "orbit" about the galactic center is quite suspect.
     
    Last edited by a moderator: May 13, 2012
  9. sadang Registered Member

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    20
    Why should not I have contrary opinions, if I consider that the facts well accepted by actual science are founded on false premises. Why, if I still have my head over the shoulders and at least one functional synapse in my brain, I have to accept what others are trying to impose me, without looking for my own answers? Why if I see that the answers received are vague, incomplete or totally untrue, I have to close my eyes and should not observe all these?

    We both know that the actual gravitational theory is 500 years old (with 450 years older than Tesla's opinion) and is based mainly on the anterior work of Euclid. Newton used in his Principle exposure, the deductive method, although how he arrived at his results was primarily the inductive. To expose his theory following such a deductive method, he postulates from beginning, in axioms and definitions, all his absolutes (the absolute space, independent of the existence and motion of bodies, absolute rest, absolute motion...) necessary for intrinsic justification, of his mathematical artifice, which obviously preceded them.

    On the other hand I observe that you have given no response to the questions raised in my previous message! As in fact, to all direct or suggested questions raised in my previous messages, that do not conform with the scientific mainstream! Is not it the same ostrich policy, when it comes to something that science has no answer? I mean, he put his head in the sand and make not see it! Or worse, deny the existence of that issue, accusing the incompetence, or find other ways to close the mouth of heretic!

    Bellow I put a quote from my previous message to see it clearly again:

    Please, observe that I specified clearly that the Moon rotate around the galactic center, not around the Earth or the Sun. Read again "... that our Moon is not orbiting around the Earth at all! Instead it real orbiting path is around our galactic center...". Is the same analogy to your Moon not orbiting the Earth, but orbiting the Sun! With this statement you have to agree! I don't said the solar system is orbiting the galactic center. Again, this is what you have to agree "... that our Moon is not orbiting around the Earth at all! Instead it real orbiting path is around our galactic center..."
     
  10. Robittybob1 Banned Banned

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  11. AlexG Like nailing Jello to a tree Valued Senior Member

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    So you reject the facts and reject the science. What point in discussing it with you then? You take the position of the crank.
     
  12. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    No it will never happen. What you don´t seem to understand is the tidal locking forces are due to the GRADIENT of gravity forces. They decrease as the inverse CUBE of the distance, so as the separation between Earth and moon increases it is possible the moon will no longer keep the same side turned towards the Earth.

    For example if the moon revolved around the Earth (viewed from Earth) in 30 days (instead of 27.3) then the moon may forever in the future spin about its axis in 30 days - no longer in a 1 to 1 phase lock with the the Earth.

    Just to to be completely clear: In the distant future perhaps from the POV of the Earth, the moon revolves around the earth once every 40 days and spins on its axis 360 degrees every 30 days. - show all sides to the earth.

    To be more exact: assume as an example that the earth moon separation were 26% greater than now. I.e. was 1.26 times greater. Note that 1.26 cubed is 2. Thus the tidal forces would be only half as great as they are now and the period of the moon would be square root of 2 or 1.414 times greater. I.e. 27.3x 1.414 = 38.6 days long (if the day still had 24 hours) With tidal torques only half a strong as now, I doubt these torques could remove so much angular momentum from the moon - increase it current spin period of 27.3 to 38.6 24hour days, but that calculation is more difficult to do to be sure (and requires calculus, plus a lot of data I don´t have about the internal mass distribution inside the moon.)

    These things are not a matter for opinions but scientific facts - The above numbers come from the inverse cube relation of gravity´s gradient and the fact that the square of the period is proportional to the cube of the orbit radius. Get educated and stop guessing when you can be exactly correct.
     
    Last edited by a moderator: May 14, 2012
  13. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I did not ignore you analogy, but explained why it is false:
    As you were too dense (or ignorant?) to understand this reply, I will now extend it with one simple example you should be able to understand:

    The first “near miss” with a binary plus one star system will occur in 27,000 years when the Alpha Centauri system will pass only 2.36 light years away for the solar system. It is currently 4.37 light years from the solar system. As it is more than twice as massive as the solar system, it will scatter the solar system more than it is scattered by the solar system in this “near miss” From: http://en.wikipedia.org/wiki/Alpha_Centauri

    After this first near miss scattering in only 27,000 years from now, there will be many many more in the more than 200,000,000 years that follow. The solar system is relative far from the galactic center. If a near miss with a much more massive star system should occur in say 90,000,000 years from now, it is quite possible the solar system could be thrown entirely out of our galaxy before it even completes half an orbit about the galactic center.

    As we know so little about the future dynamics of the solar system in the galaxy, it is silly to say it is orbiting the galactic center, but we know that the moon will orbit about the sun in a nearly perfect ellipse for at least a million times more.

    As I told Robittbob1 in closing: Get educated and stop guessing (making up false statements) when you can be exactly correct.

    The moon orbits the sun traveling in a near perfect ellipse at about 67,000 mph and is ALWAYS curving towards the sun. The ellipse would be perfect if not for the slight deflections (less than 1/4 of one percent of the distance to the sun) the Earth´s gravity periodically makes. But don´t learn, keep you ignorance intact. - Cranks / ignorant crack-pots / make the world more interesting.
     
    Last edited by a moderator: May 14, 2012
  14. Robittybob1 Banned Banned

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    Hi BillyT - finally found something like what i had read about the future of the Earth -Moon relationship and here is something like what I had previously read.
    http://burro.astr.cwru.edu/Academics/Astr221/SolarSys/earthmoon.html

    It is an academic website so it should be fairly accurate OK and they talk of the Moon and Earth in a 1:1 Synchronous rotation. Same side of Moon always facing same side of Earth. It is well beyond me to say whether or not this will happen, but it is what I had read, so please don't pick on my education.

     
  15. sadang Registered Member

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    Excellent Billy! Excellent! Now, your policy responses to avoid uncomfortable questions, or comments on topics not comply with current scientific mainstream are becoming more obvious!

    This explanation:
    is not the explanation of my statement:
    instead is the explanation of your own statement:
    Try again with focus on the Moon, not on the entire solar system. I made that analogy intentionally, to emphasize your way of thinking. Is the same principle, only applied at a more larger scale. If the Moon revolve around the Sun, instead of revolving around the Earth, as you and the official scientific mainstream sustain, and applying the same principle of the law of gravitational force attraction, I conclude that the Moon revolves around the galactic center instead to revolve around the Sun. Is the same principle, applied to the same object, using the same gravitational force of attraction law, but only at a bigger scale!

    Try to answer or comment only about the Moon's movement! Answer clear, is the Moon itself revolve or not, around the galactic center? Just Moon, excluding from your explanation the Sun, Earth, Venus, Mars... the 10, 11, 12... planets and their moons, or any other arguments or objects you think remained still not listed.
     
  16. DaveC426913 Valued Senior Member

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    Technically, there is nothing wrong with describing the Moon as if it were rotating around the galactic centre, rather than around Earth or Sol. The Moon is influenced by A. Centauri to a small degree as well, though it does not revolve around it. (Indeed, if the Earth and Sol were suddenly whisked away, the Moon would happily continue to orbit the galactic centre.)

    The question is: how much use is it to try to describe the Moon's motion as galaxy-centred while being influenced by Earth and Sol.

    The answer is: it is only of great use if you are a masochist.
     
  17. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    A more accurate description of the moon´s motion thru the galaxy is that of a random walk due to hundreds, if not thousands, of strong scattering events occurring before moon is even finished with half an "orbit" with other more massive star clusters but there is a long term bias to curve towards the central black hole.

    It is much like a ball in a pin-ball machine - It makes many bounces off objects but does have a long term bias to fall down the table´s slope and into the collection slot near the player´s end of the table.

    The solar system is so tiny compared to the distance from the galaxy´s central black hole that all planets and the sun are in essentially the same gravitation field that black hole produces - I.e. All parts of the solar system have the same acceleration so do not have any relative movements caused by the black hole.

    Thus, one can speak of only a part of the solar system (the Moon, Mars, Pluto, etc.) or the whole solar system when describing the motions the acceleration by the black hole makes. Again for periods, like 500,000 years or less, the solar system is much like a random walk and changing directions with each strong "near miss" scattering by another much more massive star system.

    The next significant scattering comes 27,000 years from now when the more than twice as massive Alpha Centauri system will pass only 2.36 light years away for the solar system. (It is currently 4.37 light years from the solar system.) It´s gravity gradient will still be quite small, but may make a noticeable chance in Pluto´s orbit about the sun. I.e. Pluto will not get exactly the same gravity impulse that the sun does as Alpha Centauri system passes by. Thus, unlike the central black hole, the Alpha Centauri system may be able to make a slight relative motion within the solar system.

    The only relative motions between these various parts of the solar system (like moon following essentially a perfect ellipse about the sun) is due to local gravity sources (the sun mainly) not the central black hole.
     
    Last edited by a moderator: May 14, 2012
  18. sadang Registered Member

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    @ Billy T
    The argument with all that scattering events that may occur over a so long period of time, as long as it take Moon to revolve around the galactic center, are effective only puerile arguments. It's just a way to divert discussion from the main theme. A specific behavior of any man, who has superior training, and is too proud due to the education and his social attribute (with which he identifies permanently, total forgetting about the man behind the attribute), to recognize that he is in trouble.

    As I said in the first messages, it is not about you or me, it is about the real facts, not yours, mine, or scientific community. We all have brain, and have to think with it, and not accept what someone else says, no matter who that person is. If you will continue in this way, using copy-paste from wikipedia, or making different assertion, only trying to confuse or divert the discussion from the main theme, I feel compelled to tell you that you hurt yourself, but especially others who trust you. I know you will not happy accept these words, but that's okay. In life, never is too late to learn! We, all our life learn ... of course if we have an open mind and the courage to ask questions and seek answers! Mainly, beyound the school book.

    @DaveC426913
    You are the Man! Great man, with great brain, and deep thinking! And you are right, I am a masochist, an ignorant, a silly guy, whatever will go to your head. Does not bother me! You are not the first nor the last with such behaviors and ways of thinking! The greatest USE in trying to describe the Moon's motion around the galactic center, is making others to think for themselves! You can?
     
  19. DaveC426913 Valued Senior Member

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    Well, we've gone around the galaxy 20 times since Sol's formation and haven't drifted all that much. The circular orbit with perturbations is a far more accurate model than a random walk.

    Our SMBH is estimated to be about 4 million solar masses. That is a microscopic fraction of the mass of the MilkyWay galaxy, which masses near 1.25 billion solar masses. This means that the SMBH's effect is negligible compared to the far larger effect of the sum total of stars gas and dust.

    According to Wiki, it will only get as close as 3.26ly - 75% of its current distance.
     
  20. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Yes, I agree that sun is old enough to have made ~20 trips around the galaxy, as in the long run the bias on the short term random walk will always win as it is NOT random. I said:
    Thanks for catching my accidental exchange of 3.26 into 2.36
     
  21. wroberson Registered Member

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    Maybe the Moon is spinning. It may be spinning so fast, it's creating an optical illusion where we only see one side. You can discover it yourself by spinning a coin on the table or by watching a ceiling fan. Sometimes these things look like they are spinning backwards.

    another idea has to do with the creation of the Earth-Moon System. Some say an asteroid went through the Earth and achieved a close orbit. Others say the moon was captured by the Earth. I have a different idea. Earth's gravity is not strong enough to capture anything with enough momentum. It takes all the gravity on Earth to keep the furniture on the ground.

    As for an asteroid going through. I would rather say from. It's very simple. At one point this planet was a molten ball. Thin layer of crust formed. A massive volcano erupted from the weakest point and emptied the seas of magma and created a moon. An earthquake followed breaking the thin layer of crust . The continents fell together to create one super continent. Gases were released into the atmosphere and it rained oceans of water. And then the entire system cooled off, froze and shrank to it's present condition.
     
  22. 420randomness Registered Senior Member

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    maybe because of the man on the moon!
     

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