Trouble with binary planets.

[burke111]

Okay, I know this has been posted before, but I don't think in the past year, so I am not sure if there have been any updates to functionality. I have followed the different steps in the threads I've found, but can't get it to work.

What I am trying to do:
Create a pair of earth-like planets that orbit each other while orbiting a central star. The two earths are 1.9 and .88 earth masses and are about midway through the habitable zone of a low-end, F-type star.

What I have done:

Version 1:

• Step 1: Pause/Enter Edit Mode
• Step 2: Create both planets, approximately .03-.08 AU apart
• Step 3: Select both planets
• Step 4: Apply "Make Binary Orbit"

Result: Both planets plummet toward the star.

Version 2:

• Step 1: Pause/Enter Edit Mode
• Step 2: Create both planets, approximately .03-.08 AU apart
• Step 3: Select both planets
• Step 4: Apply "Make Binary Orbit"
• Step 5: Apply "Add Barycenter"

Result: Both planets plummet toward the star.

Version 3:

• Step 1: Pause/Enter Edit Mode
• Step 2: Create both planets, approximately .03-.08 AU apart
• Step 3: Select both planets
• Step 4: Apply "Make Binary Orbit"
• Step 5: Apply "Add Barycenter"
• Step 6: Select Barycenter and star
• Step 7: Apply "Make Binary Orbit

Result: Normal separate orbits.

Version 4:

• Step 1: Pause/Enter Edit Mode
• Step 2: Create both planets, approximately .03-.08 AU apart
• Step 3: Select both planets and star
• Step 4: Apply "Make Binary Orbit"

Result: Normal separate orbits (as I expected, but I saw the steps in a thread and thought I'd try).


About the only way I've gotten a similar result to what I am seeking is to actually make the smaller planet a moon in orbit around the larger one.

Additionally, I am curious if it'd be possible to get a small moon to do a figure 8 around the two planets, although I'm more interested in getting them to actually be binary at the moment.

Thanks for the help.

[Hellpotatoe]

Version 2:

• Step 1: Pause/Enter Edit Mode
• Step 2: Create both planets, approximately .03-.08 AU apart
• Step 3: Select both planets
• Step 4: Apply "Make Binary Orbit"
• Step 5: Apply "Add Barycenter"

Do this, and make the barycenter auto-orbit the star. I think that it should work
No, it doesnt work

[Darvince]

Unless they're equal masses you have to treat teh littler one as a moon.

[karakris]

How about -

Make Both Planets -

Add Barycentre.

Select Barycentre - and make both Planets Orbit around it.
You are thus creating a two-body Kemplerer Rosette.

Select Barycentre.
Put your Star on the Barycentre.

NOTE - This is NOT a very Stable System.

The Bigger the Star, and the further apart the Planets are - the better the Stability.
Howervr - you can only ever get RELATIVE Stability - it will go "cockeyed" in time, and then get wrecked.   

[burke111]

Unless they're equal masses you have to treat teh littler one as a moon.

Thanks. That seemed to be the issue. I now have the masses the same but densities and diameters different to give the levels of gravity I was looking for. I've got the sim going now, so we'll see just how stable it is. There is an interior planet/moon combo on the very edge of habitability that will most likely cause problems, but I'm most interested in getting the binary planets going.

The real fun will come when I try and add a brown dwarf on the edge of the system, but I'm pretty positive that it will throw everything out of sync.

[blotz]

fun for you, bad for the things living on it