Possibility of multiple planets sharing the same orbit?

[Aldarion]

TL;DR

Possibility of multiple planets sharing the same orbit?

So I remembered that Jupiter shares his orbit with two asteroid groups (Jupiter trojans) at Lagrange points in its orbit. So I want to ask, is it at all possible for planets or planetoids to be formed at Lagrange points in a star system, or will gravitational interference always ensure that it is either an asteroid field or nothing?

 

[Ibix]

I think that technically you can't have a planet, because the definition of a planet requires it to have cleared its orbit of other stuff anywhere near comparable size (excluding moons). So any object sharing an orbit with Jupiter is not a planet by definition.

Dwarf planets are possible. Have a look at the wiki article on co-orbital objects.

 

[Aldarion]

I think that technically you can't have a planet, because the definition of a planet requires it to have cleared its orbit of other stuff anywhere near comparable size (excluding moons). So any object sharing an orbit with Jupiter is not a planet by definition.

Dwarf planets are possible. Have a look at the wiki article on co-orbital objects.

By planet, I meant an orbital body large enough to be more or less perfectly spherical. So basically like Janus and Epimetheus, but orbiting a star.

 

[Ibix]

Those would be dwarf planets. The wiki article I linked lists a few objects that fit the bill - at least one of the Jupiter Trojans is larger than the two satellites you cited.

 

[FactChecker]

According to this, Only Lagrange points L4 and L5 can offer stable orbits, and then only for objects 1/25th the mass of the main planet or less.

Note: This is the first time I have noticed a DuckAssist AI(?) answer. It seemed very helpful.

 

[DaveC426913]

According to this, Only Lagrange points L4 and L5 can offer stable orbits, and then only for objects 1/25th the mass of the main planet or less.

So, Jupiter could keep two Uranus' in his harem - one at each L.

 

[FactChecker]

So, Jupiter could keep two Uranus' in his harem - one at each L.

I am ignorant on this subject, but there might be a dependency between objects at L4 and L5 which disturbs their orbits. It might only work for one at a time. I'm afraid that I have already gotten out of my lane and should leave this for others.

 

[DaveC426913]

I am ignorant on this subject, but there might be a dependency between objects at L4 and L5 which disturbs their orbits. It might only work for one at a time. I'm afraid that I have already gotten out of my lane and should leave this for others.

I doubt it. They're 120 degrees - a billion miles - apart. That's bigger than the entire inner solar system's diameter.

Saturn and Mars are each less than half that distance.

 

[DaveC426913]

Sorry. I got my numbers wrong. Google has helpfully corrected me.

 

[Baluncore]

Google has helpfully corrected me.

That is AI for you. It is hallucinating again.

That answer has been verified here.
https://www.vedantu.com/question-an...-social-science-cbse-5fed56f0e9fb3d3419104604

 

[DaveC426913]

That is AI for you. It is hallucinating again.

It's not actually AI. It's -

waitaminnit - you're messin' with me. You found the same thing I did.

That answer has been verified here.
https://www.vedantu.com/question-an...-social-science-cbse-5fed56f0e9fb3d3419104604

Yes. I sent them a strongly-worded post.

 

[Baluncore]

Their answer is only out by one tenth of a crore.
That is 6 orders of magnitude to a human;
or 20 orders of magnitude to a computer.

 

[Filip Larsen]

When talking about mass ratios for L4/L5 stability note that the masses involved are the primary and the secondary, not the third "test" particle. So for the Sun/Jupiter system L4 and L5 is considered stable for a test particle. If the third object has mass comparable with the secondary a different (likely numerical) analysis is probably needed to establish stability. I seem to recall there are several "constructed" configurations of multiple massive objects around a primary that can be shown to have periodic trajectories, e.g. like the Klemperer rosette, but if one want to only considered "natural occurring" co-orbiting configurations I would would expect most of those configurations to be very unlikely as any configuration also has to fit into models of solar system formation.

 

[Ibix]

I would suspect that when the mass of the Trojan is such that its potential is anywhere near the depth of the L4/L5 potential well then you need to do some proper analysis. That's just a guess, though - Spivak's book (referenced in @FactChecker's link in #5) might shed more light.

 

[Aldarion]

Thanks!