Celestia Forums

Would this just be too far out there? Could a double planetary system support having a shared moon, with the moon equal distant from each planet? The moon would sit on the barycenter and not move, or maybe wobble just alittle.

Thanks
Tim

I want to say "No."

For the same reason an Earth can't exist on the other side of the sun.

But I don't know for certain.

That would be unstable, because the gravitational force increases with decreasing distance. A small perturbation towards one of the planets would therefore cause the "moon" to experience a net force towards that planet, which would cause the perturbation to grow.

In the image you posted, gravity alone wouldn't allow it to be stable. If they were continuously stablized using some kind of massive futuristic worldmoving superrockets, then they can remain in that configuration. If not stablized, they'd wind up in some other kind of orbits.

Celestia can simulate your idea because Celestia doesn't have gravity.

It is possible for one of planets to have a moon or multiple moons. It is also possible for a moon to orbit both planets, which is what I first thought when I read the title of this post.

Type PSR 1620-26 into Celestia to see a circumbinary planet of a pulsar and white dwarf.