# Thread: Possible correlation between sun's spin and precession of orbit of planets

1. ## my penny's worth

I've thought about this Mercury precession another way, that it is a 'momentum transfer' from the Sun's equatorial spin also, but that the numbers did not work out (though I had no way to work them out since I don't know this math) because Mercury was assumed to act as it's mass was computed from Newtonian orbital mechanics, then adjusted with GR. I thought (and this is my penny's worth) that if the mass was acting 'as if' it were, per equivalence to G, much less than measured (though remaining same mass), that this close body to the Sun would 'accept' more momentum transfer than Newtonian mechanics would allow. If, for example, Mercury's total mass acted 'as if' it were only about 40% (at about 0.39 AU) of what we know it to be, then the momentum transfer from the Sun would act as if it were 2 1/2 times what Newton's would calculate. But I never did the math, nor do I know at this point how to do it, so leave this here more as a doodle than a serious proposition. Otherwise, Grav, I am impressed with the work you did here!

2. Order of Kilopi
Join Date
Nov 2002
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6,235
Originally Posted by grav
It would appear that the precession of the planets due to the sun's spin might have some similarities with this effect, as provided by Tensor in a somewhat related thread.
Actually grav (and you too nutant , I'm not sure if you've heard the explanation before), the GR precession is a second order effect of gravity. Here's a way to think about it. In GR, gravity is non-linear and couples through stress-energy. The sun's gravitation field can be considered to have an amount of energy, which gives rise to an additional amount of gravity in the second order that causes the precession. Now, obviously, this is just an analogy. You have to go the math to find the effect. The extra gravity doesn't show up in the first order (which is basically equivalent to Newtonian gravity), only in the second and higher orders.

3. I have noticed that the sun's spin constant, (v/c)*R, is really just an additional distance aquired by planets during orbit, regardless of whether Einstein's formula is used or mine. In other words, each planet gains an additional distance of (v/c)*R=4629.5525 meters for the sun, per orbit. This is the recession. For elliptical orbits, it would appear that the entire orbit turns this distance for each orbit of the planet itself.

As it also turns out, the ratio of the Schwarzchild radius to the radius of the sun is about the same as the ratio of the time light takes to travel the radius of the sun to the time for one rotation, or (2GM/c^2)/R=(R/c)/T, but I guess that is probably what you were referrrin to, Publius.

Now, I have been trying to relate this to other phenomena. It isn't that easy to find known precessions. However, the thread on Mond theory in this ATM section has been helpful. Apparently there is a formula for acceleration that is about (a*a0)^1/2 when a<a0. That is, when the Newtonian value for a is smaller than a0, which is some constant acceleration, the formula works out. When a is much larger than a0, then just a is used. Of course, it doesn't really make sense that there should be two seperate formulas for when a is less or greater than a0. I looked up galaxy rotation curves, as referred to in the same thread, and apparently the velocity of galaxies evens out with distance, and becomes a constant. This actually agrees with the formula for acceleration.

Well, the formula for (a*a0)^1/2 breaks down to [(GM/d^2*a0)^1/2]=[(GM*a0)^1/2]/d. The numerator is a constant in this case, so the acceleration is inversely proportional to the distance, the same as for the precession of orbits. But since the precession of orbits is really just in addition to the normal distance travelled, then perhaps this is too. In other words, the acceleration as presented in this way may really just be in addition to the normal Newtonian acceleration, or a'=a+(a*a0)^1/2=GM/d^2+[(GM*a0)^1/2]/d. Since all terms are constants except for the distance, one can easily see that for small distances, GM/d^2 would be the dominating value, which is the Newtonian value, while for large distances, [(GM*a0)^1/2] would dominate, and would produce a "terminal" velocity. Since a=[(GM*a0)^1/2]/d for very large distances, and a=v^2/d also, then v^2=(GM*a0)^1/2, and the terminal velocity would be v=(GM*a0)^1/4, although I still cannot speculate yet the term of a0 might really mean.

4. ## If only it were this simple...

Originally Posted by nutant gene 71
I've thought about this Mercury precession another way, that it is a 'momentum transfer' from the Sun's equatorial spin also, but that the numbers did not work out (though I had no way to work them out since I don't know this math) because Mercury was assumed to act as it's mass was computed from Newtonian orbital mechanics, then adjusted with GR. I thought (and this is my penny's worth) that if the mass was acting 'as if' it were, per equivalence to G, much less than measured (though remaining same mass), that this close body to the Sun would 'accept' more momentum transfer than Newtonian mechanics would allow. If, for example, Mercury's total mass acted 'as if' it were only about 40% (at about 0.39 AU) of what we know it to be, then the momentum transfer from the Sun would act as if it were 2 1/2 times what Newton's would calculate. But I never did the math, nor do I know at this point how to do it, so leave this here more as a doodle than a serious proposition. Otherwise, Grav, I am impressed with the work you did here!
This is a follow up on this above, where I worked out the numbers. Intriguing, if only it were so simple...

You can find the actual numbers here: http://www.humancafe.com/discus/mess...65300#POST1733

Just a thought, that 'solar angular momentum' has something to do with Mercury's 43" per century precession. The math seems to work, as if it were so, though not a 'proof' per se. Result works out for 43 arc seconds per century as:

(delta) d_century = ~11,750,400 meters/century, or ~11,750.4 km/cy (vs. real 11,944 km/cy) -- over a 5 day period at Merc's perihelion.