Why Mercury's precession is not as big as Earth? (5.75" < 11.45")

Discussion in 'Astronomy, Exobiology, & Cosmology' started by TonyYuan, Apr 7, 2020.

  1. TonyYuan Registered Senior Member

    Messages:
    432
    We all know that Mercury's precession is the largest, but from the observed data, why is Mercury's precession not as big as Earth? ( 5.75" < 11.45" ) This makes us very confused, hoping to get an answer here. Thank you.

    Table 2:The observed perihelion precession rates of the planets compared with the theoretical precession rates calculated from Equation (1024) and Table 1. The precession rates are in arc seconds per year.
    Planet

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Mercury

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Venus

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Earth

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Mars

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Jupiter

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Saturn

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Uranus

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Neptune

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!



    http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node115.html
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. TonyYuan Registered Senior Member

    Messages:
    432
    We all know that Mercury's precession is the largest, but from the observed data, why is Mercury's precession not as big as Earth? ( 5.75" < 11.45" ) This makes us very confused, hoping to get an answer here. Thank you.

    Table 2:The observed perihelion precession rates of the planets compared with the theoretical precession rates calculated from Equation (1024) and Table 1. The precession rates are in arc seconds per year.
    Planet

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Mercury

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Venus

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Earth

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Mars

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Jupiter

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Saturn

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Uranus

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Neptune

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!



    http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node115.html
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. TonyYuan Registered Senior Member

    Messages:
    432
    Can anyone explain this observed planetary precession data?
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. Q-reeus Valued Senior Member

    Messages:
    3,643
    You are confusing the magnitude of the tiny GR correction to perihelion advance with the much greater planetary perturbations calculated using Newtonian physics.
    The article you cited explains how to estimate those and why there is no simple monatonic progression with radius from the sun.
    Also, this thread belongs in Astronomy, Exobiology & Cosmology section, not Earth Science.
     
  8. Q-reeus Valued Senior Member

    Messages:
    3,643
    Someone's out to screwing around with me. No sooner do I post a reply than it disappears. Here it is again (from memory):

    You confuse the tiny GR correction to perihelion advance with the much greater perturbative contributions from all the other planets - calculated using Newtonian physics.
    The article you cite shows how those are calculated and explains why there is no simple monatonic dependence on radius from the sun.
    Also, this thread belongs under Astronomy, Exobiology & Cosmology section, not Earth Science (now done).
    [PS - well my original post IS still there - under Earth Science! So I must guess the OP has simply ADDED a copy to A, E & C section. Presumably that situation won't last long.]
     
    Last edited: Apr 8, 2020
  9. TonyYuan Registered Senior Member

    Messages:
    432
    What you mean is that in the solar system, Mercury's precession is not the most obvious considering factors such as planetary interference.
    Is it only the GR effect that has the most obvious effect on Mercury precession? Thanks.
     
  10. TonyYuan Registered Senior Member

    Messages:
    432
    What you mean is that in the solar system, Mercury's precession is not the most obvious considering factors such as planetary interference.
    Is it only the GR effect that has the most obvious effect on Mercury precession? Thanks.
     
  11. paddoboy Valued Senior Member

    Messages:
    25,671
    I believe its simply the fact that Newtonian mechanics was simply not accurate enough to explain the total precession, and the additional fact that spacetime itself was being dragged around by the much larger mass of the Sun, as explained by GR.
     
  12. paddoboy Valued Senior Member

    Messages:
    25,671
    https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury

    "Under Newtonian physics, a two-body system consisting of a lone object orbiting a spherical mass would trace out an ellipse with the center of mass of the system at a focus. The point of closest approach, called the periapsis (or, because the central body in the Solar System is the Sun, perihelion), is fixed. A number of effects in the Solar System cause the perihelia of planets to precess (rotate) around the Sun. The principal cause is the presence of other planets which perturb one another's orbit. Another (much less significant) effect is solar oblateness.

    Mercury deviates from the precession predicted from these Newtonian effects. This anomalous rate of precession of the perihelion of Mercury's orbit was first recognized in 1859 as a problem in celestial mechanics, by Urbain Le Verrier. His reanalysis of available timed observations of transits of Mercury over the Sun's disk from 1697 to 1848 showed that the actual rate of the precession disagreed from that predicted from Newton's theory by 38″ (arc seconds) per tropical century (later re-estimated at 43″ by Simon Newcomb in 1882).[6] A number of ad hoc and ultimately unsuccessful solutions were proposed, but they tended to introduce more problems.

    In general relativity, this remaining precession, or change of orientation of the orbital ellipse within its orbital plane, is explained by gravitation being mediated by the curvature of spacetime. Einstein showed that general relativity[3] agrees closely with the observed amount of perihelion shift. This was a powerful factor motivating the adoption of general relativity".
     
  13. Q-reeus Valued Senior Member

    Messages:
    3,643
    I wouldn't word it that way. As a crude guide one expects outer planets to be perturbed more (at least in terms of angular advance per orbital revolution) by inner planets of similar mass than vice versa in rough analogy to shell theorem. But planetary masses are far from similar and also degrees of eccentricity vary much. One has to work through all the details and see what comes out at the end.
    GR principal contribution is kind of midway in magnitude, but thanks to the level to which the other Newtonian effects have long been known, that observed 'discrepancy' accurately matches GR theory - which pleased Einstein no end. Wikipedia lists the relative contributions:
    https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury
    I'm taking a gamble and only posting this in the A, E & C version of your thread, as I expect the original one under Earth Science will be deleted sometime down the track.
     
  14. TonyYuan Registered Senior Member

    Messages:
    432
    Mercury

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(5.75-5.50)=25"
    Venus

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(10.75-2.04)=871"
    Earth

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(11.87-11.45)=42"
    Mars

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(17.60-16.28)=32"
    Jupiter

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(7.42-6.55)=87"
    Saturn

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(19.50-18.36)=114"

    Precursor deviation calculated by GR: 100* 0.0383/(R_planet/R_earth * T/365.24) , T is the revolution period of the planet around the sun.
    Mercury:43"....PK...25"
    Venus:8.61" ....PK...871"
    Earth:3.83"....PK...42"
    Mars:0.35"....PK...32"
    Jupiter:0.062"....PK...87"
    We know that GR's calculation of precession deviation is very accurate, but we can't see from these data. Is there something we have done wrong? Thanks.

    In general relativity the perihelion shift σ, expressed in radians per revolution, is approximately given by:[10]

    Please Register or Log in to view the hidden image!


    Through this formula shift σ * (*365.24/T_planet)*(180/3.14159) , the same precession deviation can still be obtained. There is still a large deviation from the observed results.

     
    Last edited: Apr 8, 2020
  15. TonyYuan Registered Senior Member

    Messages:
    432
    Mercury

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(5.75-5.50)=25"
    Venus

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(10.75-2.04)=871"
    Earth

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(11.87-11.45)=42"
    Mars

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(17.60-16.28)=32"
    Jupiter

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(7.42-6.55)=87"
    Saturn

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    ..........................100*(19.50-18.36)=114"

    Precursor deviation calculated by GR: 100* 0.0383/(R_planet/R_earth * T/365.24) , T is the revolution period of the planet around the sun.
    Mercury:43"....PK...25"
    Venus:8.61" ....PK...871"
    Earth:3.83"....PK...42"
    Mars:0.35"....PK...32"
    Jupiter:0.062"....PK...87"
    We know that GR's calculation of precession deviation is very accurate, but we can't see from these data. Is there something we have done wrong? Thanks.
    In general relativity the perihelion shift σ, expressed in radians per revolution, is approximately given by:[10]

    Please Register or Log in to view the hidden image!


    Through this formula shift σ * (*365.24/T_planet)*(180/3.14159) , the same precession deviation can still be obtained. There is still a large deviation from the observed results.
     
  16. TonyYuan Registered Senior Member

    Messages:
    432
    Table 2:The observed perihelion precession rates of the planets compared with the theoretical precession rates calculated from Equation (1024) and Table 1. The precession rates are in arc seconds per year.

    "the theoretical precession rates calculated from Equation (1024) and Table" , is this the data obtained through GR, or through classical mechanics calculations?
    for example:
    Mercury

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!

    , 5.50 is obtained through GR or classical mechanics?
    Q-reeus, I hope you can help me clear this doubt. Thanks.
     
  17. Q-reeus Valued Senior Member

    Messages:
    3,643
    Feeling some bad vibes now. Skimming back over earlier posts in other threads, a certain pattern emerges. I suspect another member is thinking Theorist etc. etc. is back yet again.
     
    exchemist likes this.
  18. TonyYuan Registered Senior Member

    Messages:
    432
    I can't understand the information you said, can you explain it, because I really don't know the history of this story.
     
  19. TonyYuan Registered Senior Member

    Messages:
    432
    https://photos.app.goo.gl/axeDPZggPZAjComR7
    Assume that the earth speed v0 = 0. Star began to approach the earth at the speed of v. Star came to position B, and the elapsed time was T seconds. The gravitational changes experienced by the earth are as follows:
    A: F = G * M * m / R^2
    B: F = G * M * m / (R + 1000)^2 ≈ G * M * m / R^2

    According to the law of conservation of momentum:
    F * T = mv1-mv0 = mv1, then v1 = F * T / m = T * G * M / R^2
    T = 2s: v1 = 2 * G * M / R^2
    T = 1s: v1 = 1 * G * M / R^2

    Because of the speed v of the star, the earth obtained a different speed v1. The larger v is, the larger v1 will be, but the gravitational force on the planet from the star has hardly changed. If the star's v = X * cos(wt), then the speed change of earth will also show volatility.
    The relative speed between them really affects the speed of the earth. Do you still think there is no Doppler effect between them? If you understand the Doppler effect, you will know that it exists anywhere.

    https://photos.app.goo.gl/FNohkKDepHhgx2b29
    To simplify the calculation, we do not consider the displacement in the y direction.
    F = G*M*m/L^2=G*M*m/(R - r*cos(w*t))^2
    F * t = mv1-mv0, assume v0=0 then F * t = mv1, then v1 = F * t / m = t*G*M/(R - r*cos(w*t))^2, then v1 = g(t)*t, g(t) = G*M/(R - r*cos(w*t))^2.
    if R>100r, v1 ≈ t*G*M/R^2 = g*t , g = G*M/R^2.


    The volatility of the gravitational field is obvious. When the celestial body is relatively far away, the g between them is close to a constant, but when they are relatively close, g is a function of relative speed and time.
    post # 119 has shown that when relative motions between celestial bodies are on the same straight line, the speed change of celestial bodies with mass m is related to the relative speed between them. If the relative speed change shows volatility, then the speed change value v1 will also show volatility. Then the gravitational acceleration g (t) will also show volatility.

    No matter what gravity is, the affected object will show volatility, it also has a Doppler effect. So I guess: if we can consider the Doppler effect of the gravitational field when calculating the precession of Mercury, then the missing 44.1 "will no longer need GR compensation.
     
  20. paddoboy Valued Senior Member

    Messages:
    25,671
    You're a nice bloke it seems Tony, but you need to take a deep breath and step back a bit.
    You will not change the premise of GR on a science forum. If you believe you have anything of value, or anything invalidating any aspect of GR, there is a proper procedure.
    In the meantime......
    https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury
     
  21. TonyYuan Registered Senior Member

    Messages:
    432
    Sources of the precession of perihelion for Mercury
    Amount (arcsec/Julian century)[8]Cause
    532.3035..................Gravitational tugs of other solar bodies
    0.0286.....................Oblateness of the Sun (quadrupole moment)
    42.9799....................Gravitoelectric effects (Schwarzschild-like), a General Relativity effect
    −0.0020...................Lense–Thirring precession
    575.31.......................Total predicted
    574.10±0.65[7]........Observed


    532.3035" I hope someone can introduce the Doppler effect of the gravitational field and recalculate it.


    Planet

    Please Register or Log in to view the hidden image!

    Please Register or Log in to view the hidden image!


    Mercury

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Venus

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Earth

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Mars

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Jupiter

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Saturn

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Uranus

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    Neptune

    Please Register or Log in to view the hidden image!

    ........

    Please Register or Log in to view the hidden image!


    If the calculation described in the previous section is carried out more accurately, taking into account the slight eccentricities of the planetary orbits, as well as their small mutual inclinations, and retaining many more terms in the expansions (1015) and (1017), then the perihelion precession rate of the planet Mercury is found to be

    Please Register or Log in to view the hidden image!

    arc seconds per year. However, the observed precession rate is

    Please Register or Log in to view the hidden image!

    arc seconds per year. It turns out that the cause of this discrepancy is the general relativistic correction to Newtonian gravity.
    5.50"------------------------->5.32", from these words, there are many things that can be tapped in this calculation model. Maybe you will be the first scholar to calculate the correct data. Introducing the Doppler effect of gravitational field, you may shock the world.

     
    Last edited: Apr 9, 2020
  22. TonyYuan Registered Senior Member

    Messages:
    432
    About post #13, #15 , I want to hear your opinion if you are willing to share. Thanks.

    No matter what gravity is, the affected object will show volatility, it also has a Doppler effect. So I guess: if we can consider the Doppler effect of the gravitational field when calculating the precession of Mercury, then the missing 44.1" will no longer need GR compensation.

    Regarding the existence of the Doppler effect in the gravitational field, I have clearly stated that the knowledge I used is the knowledge of classical physics, I believe everyone can understand it. The distance between the planets of our solar system is not far away, and this Doppler effect cannot be ignored by us. The acceleration of gravity in classical physics is an approximate formula g = G * M / R^2 when they are very far away from each other. But when they are relatively close to each other, the results calculated using this formula will have a relatively large deviation.
     
    Last edited: Apr 9, 2020
  23. exchemist Valued Senior Member

    Messages:
    9,647
    I did wonder about that, certainly. However this one seems to lack some of the characteristics of Theorist. There isn't the same level of nonsense algebra, nor the obsession with clocks, nor the telltale habit of lobbing in new bits of nonsense periodically, to keep the pot boiling. In fact this one seems utterly obsessed with saying the same - nonsensical - thing over and over again. So if it is he, then he has changed his methodology quite a bit - different drugs, perhaps?

    Please Register or Log in to view the hidden image!



    On the other hand, post 12 does sound like Theorist...
     

Share This Page