Mercury's Perihelion Precession

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Thomas</i>
<br />Could anybody point me to some original literature that describes the observations and corresponding data analysis that leads to the well known value of 43"? I have a couple of ideas how to explain this value without Einsteins GR, but need to know exactly how the observations and data reductions were done.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">The analysis of astronomical data for orbit determination is not a simple subject. Classically, the work of L.V. Morrison is often cited. With modern observing techniques, see Standish's JPL technical reports. But I doubt you are ready for that many technical details.

In essence, the analysis determines the best-fitting ellipse with the Sun at one focus on each revolution of Mercury. It then measures the rate at which that ellipse precesses forward. If you focussed on what you really want to know, perhaps you could be spared years of study needed to truly understand and/or duplicate the data analysis. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
The analysis of astronomical data for orbit determination is not a simple subject. Classically, the work of L.V. Morrison is often cited. With modern observing techniques, see Standish's JPL technical reports. But I doubt you are ready for that many technical details.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I was not thinking of general works regarding orbit determination but specific papers (preferably modern ones) where the 43" value has actually been derived.
Don't worry about technical details. I'll be able to figure out the points that interest me.

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<i>Originally posted by Thomas</i>
<br />You will find the numerical values from Morrison & Ward's solution, together with the reference, in the 2nd last paragraph before the "Gravitational Shielding" section near the end of this paper:
metaresearch.org/cosmology/gravity/possi...pertiesofgravity.asp
For the results of other data analysts, try a literature search at adsww.harvard.edu [Sorry, you will need to cut and paste this link and change the first part from "adsww" to "adswww" because the message board software doesn't parse it correctly when the three w's are written here.] -|Tom|-

Thanks for the references.
I had a look at Morrison and Ward's paper (which analyses Mercury transits to determined the precession) and also at a corresponding numerical N-Body calculation by Narlikar and Rana ( adsabs.harvard.edu/cgi-bin/nph-bib_query?1985MNRAS.213..657N ). From the latter it is apparent that the total precession fluctuates actually quite strongly with several periods. It is therefore somewhat unclear to me if the excess figure of 43" is only a long term average or a value that applies at any specific time instant.

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<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Thomas</i>
<br />the total precession fluctuates actually quite strongly with several periods. It is therefore somewhat unclear to me if the excess figure of 43" is only a long term average or a value that applies at any specific time instant.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Celestial mechanics divides perturbations into "periodic" and "secular", where the latter means progressive and the former means repeating. The major planets perturb Mercury's orbit in many ways, both periodic and secular. In analytic theories of the motion, it is customary to separate the two types of perturbations -- something numerical integrations cannot do. Then the total secular advance of the perihelion of Mercury predicted by Newtonian gravity is 532"/cy, and the observed advance is 575"/cy (both numbers from memory). The difference is 43"/cy, the part explained only by GR and later field theories of gravity.

Here is another reference with a modern determination of the excess advance: Celest.Mech.&Dyn.Astron. 55, 313-321 (1993): Pitjeva, E.V., “Experimental testing of relativity effects, variability of the gravitational constant and topography of Mercury surface from radar observations 1964-1989”. The excess perihelion advance derived from these modern radar observations is 42.95”/cy. -|Tom|-

What I find rather questionable in these works is that they use heliocentric coordinates throughout when the sun is in fact not an inertial system as it orbits the barycenter of the solar system (with a period corresponding to mainly the orbital period of Jupiter and a radius of about 7*10^5 km). In the barycentric system there is consequently an additional centrifugal force which should be taken into account as the positional observations of the planets as well as any time corrections are referred to the fixed stars.

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