Can Two Equal-Mass Planets Share a Satellite?

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Discussion Overview

The discussion revolves around the feasibility of two equal-mass planets sharing a satellite, exploring the dynamics of such a system, including orbital characteristics and stability. The scope includes theoretical considerations and conceptual clarifications regarding celestial mechanics.

Discussion Character

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

Main Points Raised

  • One participant suggests that a satellite could orbit around the center of mass of the binary system formed by the two equal-mass planets.
  • Another participant questions whether the satellite's orbit would be less spherical, implying a potential for non-circular orbits due to gravitational interactions.
  • A further response indicates that the orbit of the satellite could indeed be perturbed by the presence of the two gravitating bodies, depending on their relative positions and the satellite's initial conditions.
  • One participant references complex Newtonian orbits involving multiple bodies, hinting at unusual orbital behaviors but does not provide specific details or sources.
  • A participant expresses concern about the stability of such a system, questioning whether it would be unstable.

Areas of Agreement / Disagreement

Participants express varying views on the nature of the satellite's orbit and its stability, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion does not resolve the assumptions regarding the initial conditions of the satellite's orbit or the specific gravitational influences of the planets on the satellite.

Semaphia
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If you had a pair of celestial rotating in a circle, both of equal mass size. Would it be possible for the planets to have a shared satellite?

Thank you for reading, Alex
 
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Sure. Put the satellite into a large orbit around the centre of mass of the binary system. That's how trinary star systems (such as Centauri) work.

(But you were probably thinking of a satellite whose orbit switches between the two parents, weren't you?)
 
Would you expect the orbit of the satellite to have a less spherical orbit?

Thanks
 
Semaphia said:
Would you expect the orbit of the satellite to have a less spherical orbit?

You mean less circular? Even with one gravitating body, there's no reason a satellite should have to be in a circular orbit. It depends on the relative amounts of energy and angular momentum in the satellite. If the satellite started in a circular orbit about a single body, the addition of another gravitating body would certainly perturb that orbit. The amount it was perturbed would depend upon the relative separations of the satellite and the gravitating bodies.
 
There are weird Newtonian orbits with, for example five bodies, where one body "is dirven to infinity in a finite time". Sorry I don't have a link for this statement, I read the paper about 20 years ago.
 
Okay, thank you very much everyone. Alex
 
wouldn't that be very onstable?
 

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