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Q & A: What locks the Moon?

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Most recent answer: 03/08/2015
Q:
I would like to ask a question concerning the moon and quantum locking/levitation. .If our moons centre contained yyitrium barium copper oxide coated saphire or another similar superconductor ,would the earths magnetic field be enough to lock electrons in the form of fluxons inside this superconductor centre and with initial inertia from the big bang create the moons sustained orbit also explainig why it has eliptical orbit as magnetic forces stronger at the poles of earth.
- david ranford (age 36)
Gloucestershire u.k
A:

The thought that magnetism might be the reason that the Moon's rotation is locked to its orbit, with the same side always facing the Earth, is kind of a natural thing to think, if you've ever watched a compass needle stay lined up pointing at another magnet. It was the first scientific idea I had as a kid, way back in 1958.  It turns out to be wrong. 

The Moon just isn't magnetic. The locking comes from ordinary gravitational tides induced by the Earth on the lunar dust. Before the Moon's spin locked in, those tides made friction and slowed the spin down. Now that the spin is locked to the orbit, there are no tidal changes on the Moon. We discuss some of these issues here: https://van.physics.illinois.edu/qa/listing.php?id=19644.

The average temperature of the Moon isn't low enough to drive YBCO superconducting, even if any were somehow present deep inside. If the Moon did have some magnetic flux trapped in some superconductor, it would interact very weakly with the Earth's field, which is only ~10-6 Oe (very rough estimate) near the Moon. So I'm afraid neither ordinary ferromagnetism nor superconducting diamagnetism plays a role in the Moon's orbit and spin.

As for the ellipticity of the orbit, pretty much all orbits are elliptical. Your countryman, Isaac Newton, showed that elliptical orbits are a direct consequence of the simple inverse-square gravitational law. Many of the orbits we see are pretty close to circular because more elliptical ones are more likely to get disrupted by close encounters with other objects.

Mike W.


(published on 03/06/2015)

Follow-Up #1: making orbiting superconductor

Q:
Thankyou very much for taking the time to reply to my earlier question .Firstly i would like to explain that i have never really had any understanding of basic physics until very recently and this was my first question to anyone using the world wide web and for your reply i am grateful. Secondly i am a person who likes to build things to show myself that i can, would replacating my theory myself on a small scale with a spheroid magnets and ybco be possible at all. Would it(ybco,disc)orbit(spheroid magnets of enough strength) given a low enough temperature and inside a vaccum be a pointless effort on my part . All be it that i understand you explained that it isnt connected to the moons orbit, but could this type of orbit occur on earth. Thankyou for your time .
- david ranford (age 36)
Gloucestershire u.k.
A:

This sounds like a fun experiment. I think it would be much easier to have the superconductor fixed and the magnet orbiting. The reason is that the superconductor should be sitting in a little cup of liquid nitrogen to stay cold, and that's hard to arrange if it's swinging around. The magnet could just be suspended from a string and swung in elliptical orbits. At least initially, you wouldn't need a vacuum to see what happens. What will be the effect on the orbit and spin of the interaction of the magnetic field and the superconductor? I'm not sure offhand, so that may add to the fun of the experiment.

You could play with things like this even without a superconductor. The moving magnet would generally induce eddy currents in a good conductor, say a ball of copper or aluminum. Those in turn exert forces on the magnet. The general effect of eddy current is to dissipate heat via the Joule heating due to the currents. The energy would come from the orbit. Again, I'm not sure offhand what effect this has on locking the orientation of the magnet . It should depend on the relative orientation of the magnetic axis and the (vertical) rotation axis.  In this experiment you could also have the conductor orbit on a string an keep the magnet fixed in various orientations.

If you do any of these experiments, please let us know how they come out.

Mike W.

 


(published on 03/08/2015)

Follow-up on this answer.