Could you have three planets in one orbit?

[TheManicMonocle]

So, as we all know the earth goes around the sun, following a usual path. Could you have three planets in one orbital path? Assuming these three planets were approximately equidistant from eachother at any given time and assuming these three planets were all approximately the same distance from the sun, or any star.

[Tyndmyr]

oddly enough, I think we just had a topic about this.

The answer is yes, via a 6-body Kempler Rosette, in which alternating bodies are roughly moon sized, and the others approximately earth sized.

[factotum]

A Klemperer rosette is not a stable orbital configuration, though, even with six members. Eventually oscillations will start in the orbits with the usual long-term consequence of that--e.g. planets colliding or being thrown into different orbits.

[Tyndmyr]

A Klemperer rosette is not a stable orbital configuration, though, even with six members. Eventually oscillations will start in the orbits with the usual long-term consequence of that--e.g. planets colliding or being thrown into different orbits.

This was discussed previously. It appears, via simulation tests, that six may indeed be quite stable. Part of this revolves around how the simulation is done, but some simulations seem good for exceptionally long lifetimes(Ie, life could form and die off, and additional planets outside the rosette do not disrupt the stability).

It is likely generally less stable than a single world, but instability is not wholly binary.

[factotum]

OK, then how would a structure with six members--three of which have to have identical masses, and the other three have to have a lower identical mass--all spaced sixty degrees apart in the same orbit occur naturally? I think you'd have to assume such a thing had been created artificially.

[Kato]

Wait, why can't you have just three? Why do they even need to be equidistant? I mean, assuming their mass/distance relation is small enough to be negligible, it seems to me there is no problem either way?

[Lvl 2 Expert]

What you can definitely have is one big one dominating the orbits of smaller bodies. Multiple of those can be moons, at least one can be orbitally locked like Pluto is to Neptune (Pluto goes round the sun three times for every two laps of Neptune in a regular fashion) and I think you might just be able to combine that with at least one more large body in some other type of quasi-satellite configuration.

The bigger the difference in size between the sun and the main planet on one side and the smaller planets on the other, the better. A decent example might be Jupiter who has collections of asteroids (the Trojans) around its Lagrange points. It could probably carry earth sized planets there if it really wanted to. Along with several large moons and maybe a Pluto-like object, that's easily three semi-inhabitable planets, if your Jupiter is enough of a hot Jupiter.

[Tyndmyr]

OK, then how would a structure with six members--three of which have to have identical masses, and the other three have to have a lower identical mass--all spaced sixty degrees apart in the same orbit occur naturally? I think you'd have to assume such a thing had been created artificially.

Oh yes. Such a thing is wildly improbable in terms of happening naturally. Artificial construction seems like the easiest explanation for such, though you might be able to technobabble something about planet formation conditions. *shrug*

Kato, it's necessary to get the stabilization from the langrage points. That corrects for small perturbations. Not huge, mind you, but it does get you an orbit that doesn't immediately tear itself apart. If, say, you had five equally spaced worlds, it'd be lucky to last for a few orbits. No stabilization, so even the tiniest imbalance rapidly becomes a not-tiny imbalance. Words like "negligible" have different meanings in different contexts, and for a completely unstable system, there's really no such thing as a negligible imbalance.