Can Inclined Binary Planets Be Stable??

[@arbodox]

This is really well explained! I didn't expect such a straightforward answer to this, glad to know that the Kozai mechanism and primary oblateness are the main players here. I wonder how tidal forces can reduce the orbital eccentricity of moons and binary planets, so I'd like to see a video on that!

[@ronaldshepherd5992]

Not impossible to God. He created EVERYTHING

[@seedmole]

I think it makes a lot of intuitive sense that a vertical arrangement would be unstable, considering simple demonstrations of angular momentum. If the two-planet system is rotating about its center, and the sun's gravitational field then acts on that rotating two-body system, then we should see some sort of precession in the axis of that two-body system. Naturally there would be some stable configuration, which apparently is right around +/- 40 degrees from the horizontal.

[@matthiasmartin4355]

Very insightful. Thanks for explaining.

[@pacegames5928]

Im literally here because i want to make a dnd setting with binary planets and didn't know if it was physically possible, thank you so much you're amazing!!

[@NorasGuidetotheGalaxy]

Good luck with your game!

[@NoahFriedman]

Why does oblateness reduce the kozai-lidov effect?

[@NorasGuidetotheGalaxy]

That's a great question! The Kozai-Lidov effect is triggered by perturbations from the third body (in this case, the star). Oblateness of the primary/secondary bodies (the planets here) also introduce perturbations, and that can be enough to prevent the weaker perturbations from the star from putting the system in the state that drives Kozai-Lidov cycles. An oblate spheroid doesn't have quite the same gravitational field as a perfect sphere--for example, it breaks some of the symmetry.

[@kayakMike1000]

I always wondered if there was a point at which where a moon and planet barry center was between the two... But the tidal forces somehow dont rip the planetoids apart...

[@copperml]

Are there general conditions for the stability of hierarchical orbits? For stars I've seen the condition that the ratio of periods should exceed 5:1. Is that generally accepted?

[@xplayfan1500]

I'm wondering, in your simulations, it showed that eventually. These binary planets would collide. Would there be any evidence left behind that it was a binary planet? I'm guessing it would depend on the type and size of planet.

[@NorasGuidetotheGalaxy]

I don't think so! The debris from the collision would either accrete onto the resulting single body or eventually be removed from the orbit.

[@xplayfan1500]

So we'd have to actually find one and witness it. Otherwise we would never know. Aww schucks.

[@nirorbach8046]

I think the weird ways Uranus and Venus revolve are evidence of a past collision...

[@kayakMike1000]

Is there a Roache limit?

[@nirorbach8046]

In the original 3 body problem when all the masses are points, there is no meaning of Roche limit. It becomes relevant only when one goes away from point like objects...

[@prathmeshrai8910]

This kindaa women is what we need

[@Jellyman1129]

Pluto and Charon prove that yes, inclined binary planets can be stable.