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B Jupiter's gravitational pull on the Sun and Earth

  1. Nov 22, 2016 #1
    I was watching a show on one of the science channels a couple of nights ago and I think I heard that Jupiter's gravitational pull on the sun is around half a million miles (or could have been kilometers).

    Now, depending on Jupiter's position in relationship to Earths, at any time does it affect the Sun-Earth distance?

    For example, if it happened that Jupiter was at opposition at the same time we were at perihelion would the distance between Earth & the Sun be a little less than the (roughly) 147 million kilometer Earth-Sun distance. Or if Jupiter is at conjunction is our distance increased? Or does the sun just pull/push us along at roughly the same distance, regardless of what Jupiter's effect on it is?


    thanks.
     
  2. jcsd
  3. Nov 22, 2016 #2

    Drakkith

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    Absolutely. Earth's orbit is affected by all the objects in the solar system, Jupiter included.

    Good question. I think the net effect of Jupiter's influence is to rotate our orbit over time, termed apsidal precession. I'm not sure of the short term effects, but I believe the distance may be a bit larger at perihelion when Jupiter is in opposition.
     
  4. Nov 22, 2016 #3
    Jupiter's gravity *will* affect Earth/Moon orbit, albeit over very long time. Precession of nodes, and stuff like that. IIRC, influences of Jupiter & Venus have similar orders of magnitude...

    Then you've their contributions to the dynamic equipotential 'Lo Roads'.
    https://en.wikipedia.org/wiki/Interplanetary_Transport_Network

    "...that Jupiter's gravitational pull on the sun is around half a million miles (or could have been kilometers)."
    I fear you've misheard. As it stands, that makes no sense. Anyone figure what was meant ??
     
  5. Nov 22, 2016 #4
    Best guess ( since the show was not referenced )
    barycentre
    https://en.wikipedia.org/wiki/Barycenter

    Sun/Jupitor barycentre lies close to the sun surface - radius of sun rounded off to 700,000 km, again rounded off to 500,000 miles.
     
  6. Nov 22, 2016 #5
    I wish I could remember the name of the show, I often have one of the science channels on when I'm reading or doing other things, and this was the case here. I will just assume then whatever the show was it was incorrect, since I'm pretty sure it clearly stated that Jupiter actually pulls the sun towards it - this is what drew my attention to it from what I was reading at the time. Perhaps it had something to do with another thing I read where it is believed that Jupiter does not actually orbit the sun the way we think, but instead they orbit one another - kind of like what Nik_2213 says:

     
    Last edited: Nov 22, 2016
  7. Nov 22, 2016 #6

    Drakkith

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    It does. Well, technically it causes the Sun to orbit about the Sun-Jupiter barycenter.

    Your video is correct. Jupiter orbits around the Sun-Jupiter barycenter. Both the Sun and Jupiter are in motion around this point.

    From here: http://spaceplace.nasa.gov/barycenter/en/

     
  8. Nov 24, 2016 #7

    mfb

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    As seen by Jupiter, Sun and Earth are close together - they will both be accelerated towards Jupiter in nearly the same way. The net effect of Jupiter's gravity on Earth's orbit (from the differences in acceleration) is small, and averages out over the course of an orbit. Only small effects like the perihelion precession remain.
     
  9. Dec 2, 2016 #8

    sophiecentaur

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    The significant Wobble of the Sun, due to Jupiter's high mass is just like the effect that the Moon has on the Earth as it orbits around us.
     
  10. Dec 2, 2016 #9

    mfb

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    With the moon it is a bit easier, because you can consider the Earth/Moon system together orbiting the Sun. There is no direct analogy for Jupiter's influence, because Earth/Moon do not orbit the Sun/Jupiter barycenter.
     
  11. Dec 2, 2016 #10

    sophiecentaur

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    The parallel is quite clear, if you are just looking at a two body system. In both cases, the approximation is a fair one as a first stab.
    That's true, because the Earth's orbit passes between the Sun and Jupiter. but it's not very relevant to what happens 1. Between Earth and Moon or 2. Between Sun and Jupiter. Are you not just over-complicating this? Where would we stop?
     
  12. Dec 2, 2016 #11

    tony873004

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  13. Dec 2, 2016 #12

    mfb

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    For an accurate calculation: at an n-body simulation. For a less accurate calculation: assume a period perturbation given by the different gravitational pull of Jupiter and Sun vs. Earth/Moon. For an even less accurate calculation: ignore all those effects and use Kepler ellipses.
     
  14. Dec 3, 2016 #13

    sophiecentaur

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    My main point was that the two body situation is probably (/definitely) adequate for starters. The presentation of the multi body situation is guaranteed to scare the casual viewer.
     
  15. Dec 3, 2016 #14

    mfb

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    OP asked about the influence of a third body, you can't answer that in the two-body system.
     
  16. Dec 3, 2016 #15

    sophiecentaur

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    Yes. I was getting sidetracked.
     
  17. Dec 3, 2016 #16

    Chronos

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    Given the sun is about 1000 times more massive than Jupiter, the gravitational effect of Jupiter on the sun is pretty trivial. The sun - Jupiter barycenter is located about 1.07 solar radii from the center of the sun, so it does cause the sun to wobble slightly. That translates to about one arc minute of displacement as viewed from earth when Jupiter is offset 90 degrees with respect to earths position.
     
  18. Dec 3, 2016 #17

    Bandersnatch

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    Surely, you mean 1/4th of an arc minute.
     
  19. Dec 3, 2016 #18

    tony873004

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    Yes.
    The link I provided in post #11 above is of an n-body simulation.
    I ran the simulation twice, each time recording the Earth-Sun distance on a daily basis.
    In the first simulation, I included the Sun, all planets (Pluto too!), and the Moon.
    In the second simulation, I set Jupiter's mass to 0.

    I ran it two more times, this time recording the Earth-Moon distance.
    Here are graphs of the data.
    EarthSunDistance.GIF EarthMoonDistance.GIF
     
  20. Dec 3, 2016 #19

    mfb

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    You clearly see the yearly / monthly variation as dominant effect: The presence of Jupiter deforms the orbit a bit. A magic constant position of Jupiter would make the orbit more and more eccentric over time, but as Jupiter's position changes, the effect points in different directions over the 12-year cycle, averaging out.

    For Moon/Earth, we have such an averaging effect over 1 year already.
     
  21. Dec 3, 2016 #20

    tony873004

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    Even more so for the outer planets. Within a thousand years of applying this "magic", Saturn, Uranus, Neptune, and Pluto are all Earth-crossers. Soon after that, they start crashing into the Sun.

    Here's a simulation that runs in your browser:
    http://orbitsimulator.com/gravitySimulatorCloud/simulations/1480799423788_jupiterStationary3.html
    The time-step self-adjusts to handle the close passes and collisions.
     
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