Binary planets just spiral inward to the star

[deoxy99]

How come I can't make binary orbits seem correct? Sometimes binary planets just spiral inward to the star.

[Dan Dixon]

How come I can't make binary orbits seem correct? Sometimes binary planets just spiral inward to the star.

Describe the steps you're taking to do this. i.e.: What you select, how many, what button you hit.

[deoxy99]

I select any two planets, and click barycenter and then click create binary orbits, but planets just spiral in.

[atomic7732]

The momentum is probably slowing the planets net force backwards more (since on has to eventually go backwards), causing both planets to lose thier inertia, and spiral in.

[Dan Dixon]

Ahh... I re-read your question and I think I understand the problem now.

If you set two planets to have a binary orbit of one another, they're not given the necessary velocity to orbit the star.

Try this in a simulation with two planets very near each other and a star:

1 - Pause the simulation.
2 - Select just the two planets.
3 - Click on binary orbit
4 - Click on create barycenter.
5 - Now just select the barycenter and the star.
6 - Click on binary orbit

Let me know if that works for you.

[deoxy99]

Nice! I just made Venus and Mercury orbit each other...but Mercury had a rotating elliptical orbit, like it had the same shape, but it just rotated around the focus...but still cool!
Thanks!

[atomic7732]

5 - Now just select the barycenter and the star.
6 - Click on binary orbit

How would this work? I though the barycenter was like Landing, just a point. Yet it could be moved and effected by gravity, I thought it was just a random point, so if you were to shoot a planet through the bary center could fly off!

[deoxy99]

It's an object isn't it? Objects orbit things.

[Dan Dixon]

The procedure is a little odd, I admit, but when you select one object and a barycenter, it applies the necessary velocity to all of the objects that make up the barycenter. In this context you could think of the barycenter as a group of objects.