Is it likely to ever discover three planets of similar mass revolving around a common barycenter, or would such a system be too unstable? Such triple planet system would look like a triangle once in a time.

  • $\begingroup$ We haven't found any yet, so probably very unlikely. $\endgroup$
    – WarpPrime
    May 21, 2021 at 17:34
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    $\begingroup$ mathematically, a 3-body system is unstable unless the ratios of mass between the 3 bodies is very high. Read up about L4 and L5 Lagrangian point requirements. Any other configuration is unstable. $\endgroup$
    – PcMan
    May 22, 2021 at 0:21
  • $\begingroup$ @PcMan and yet there are plenty of 3-body star systems, so...? $\endgroup$
    – uhoh
    May 22, 2021 at 1:52
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    $\begingroup$ @uhoh, three-body star systems are always a pair of stars orbiting each other, with a third star orbiting the pair. Such a system is always unstable in the presence of a nearby massive body (ie. a star). $\endgroup$
    – Mark
    May 22, 2021 at 2:07
  • $\begingroup$ @Mark so that's a four-body system. Just trying to clarify the "a 3-body system is unstable unless" comment. Thanks! $\endgroup$
    – uhoh
    May 22, 2021 at 2:23


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