Solar System barycenter - Orbit of planets

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Discussion Overview

The discussion revolves around the concept of the Solar System barycenter and the orbits of celestial bodies, particularly focusing on the Earth, Sun, and their respective barycenters. Participants explore the implications of these orbits, the reference frames used to describe them, and the dynamic nature of the Solar System's center of mass.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants propose that the Earth orbits the Earth-Sun barycenter while the Sun orbits the Solar System barycenter, suggesting that it is inaccurate to say the Earth orbits the Solar System barycenter directly.
  • Others argue that the gravitational influences of all bodies in the Solar System contribute to a dynamic geometry that affects orbital paths, which can be described as geodesics.
  • A participant mentions that approximating the Earth and Sun as a two-body system is useful for calculations, but may not reflect the true complexity of their interactions.
  • There is a discussion about the reference frames used to describe orbits, with some stating that the ISS orbits the Earth in a frame centered on the Earth-ISS barycenter, while others highlight the complexity when considering the Earth-Moon barycenter.
  • Some participants express uncertainty about the fixed nature of the Solar System's center of mass, noting that it varies with the positions of the planets, particularly the gas giants.
  • Concerns are raised about the perceived influence of Jupiter's gravity on the Sun, with one participant suggesting that the gravitational pull is negligible and that the center of mass is near the center of the Sun.
  • Questions are posed regarding the calculation of gravitational forces and the center of mass for the Earth-Jupiter system.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of the orbits and the implications of the Solar System barycenter. Multiple competing views and interpretations remain, particularly regarding the reference frames and the significance of gravitational influences.

Contextual Notes

Participants note the limitations of using simplified models, such as two-body approximations, and the challenges in visualizing the dynamic nature of the Solar System's center of mass. There is also mention of unresolved calculations related to gravitational forces.

  • #61
Andrew1955 said:
I am meaning, according to the best available JPL ephemerides, the planets influence on the Earth Sun distance is tiny, compared to the very large differences that would be created by (in lay persons terms) 'orbiting the solar system barycenter'.
That "in lay person's term" is the heart of the problem with this thread. You are interpreting "orbiting the barycenter" in terms of Keplerian orbits. People who say that the bodies in the solar system orbit the solar system barycenter are not talking about Keplerian orbits.
 
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  • #62
I do love a circular (elliptical) argument!
 
  • #63
D H said:
That "in lay person's term" is the heart of the problem with this thread. You are interpreting "orbiting the barycenter" in terms of Keplerian orbits. People who say that the bodies in the solar system orbit the solar system barycenter are not talking about Keplerian orbits.

>>You are interpreting "orbiting the barycenter" in terms of Keplerian orbits.

Wrong. I am interpreting it as meaning the Earth Sun distance will vary by up to to 2 million kms due to the influence of the planets. Nothing like this is observed to be happening at all.

>>People who say that the bodies in the solar system orbit the solar system barycenter are not talking about Keplerian orbits.

For my purposes there are two types of people that I need to consider:

Type 1. This type is utterly confused and has no idea of what they are talking about other than they think the SSBC has some magic abilities to cause all objects to gravitate towards it.

Type 2. This type is the kind of person you are talking about when you say "People who say that the bodies in the solar system orbit the solar system barycenter are not talking about Keplerian orbits"

If my audience had people of type 2 in it I would not have come to physics forum. I needed a method to calculate the effect of the planets gravity upon Earth so I could know by what amount the Earth Sun distance could vary as caused by the planets gravity. I now know from my calculation that in terms of the huge Earth Sun distance the amount the planets change the path of the Earth, in terms of the Earth Sun distance, is very small.

If you are challenging me on the Earth Sun distance you need to provide a reference.
 
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