# How would a binary star system with a planet with 2 moons work? If possible

I am creating a solar system that has a binary star system. The system has 3 planets. The closest being like Mercury. The next being the planet that supports life and being slightly larger then earth. And after that an ice giant similar to Neptune. My biggest interest is in the 2 moons around the 2nd planet. I want the race on the planet to use the moons and the 2 suns for religious purposes. The closest moon is mars-like in color and geography but not in size, while the further moon is similar to our moon. I would like to know if a situation like this is possible and stable, as well as the needed distances between planets, as well as the times between solar eclipses and lunar eclipses, and any other info. I will show an image of the system as well as the stats of all the objects.

Yellow star:

G2

Sol mass: 1.12

Star like are sun

Red star:

M

Sol mass: 0.42

Red dwarf

Orbital Period: 38.28 days(time tacks for stars to go around each other)

Grey planet:

Orbital period: 21.81 earth days

Blue Planet:

Ice giant

Green planet:

Year length: 419.91 earth days (234.58 days on the planet)

Day length: 1.79 earth days

Closest moon:

Mars-like

Orbital Period: 21.92 earth days

Other moon:

Moon-like

Orbital Period: 41.72 earth days

• Slight correction; it's planet, not planit.
– Sach
Dec 6 '19 at 22:48
• One problem: the blue planet is huge, in fact it's more the size of a very small star or brown dwarf. The calculations you ask for would take a lot of effort and would need more information. Key is the mass of the planets. Dec 6 '19 at 23:05
• @Sach - I have corrected this for Vexxen Dec 6 '19 at 23:06
• Oh dear, I didn't notice the size of Blue Planet. It's radius is like 4-5 times that of Jupiter I believe? That is pretty massive.
– Sach
Dec 6 '19 at 23:09
• And it is also considered impossible, since a planet's radius should only get a little larger than Jupiter's no matter how massive it gets. Dec 7 '19 at 18:58

This is possible, but you need some conditions met.

Typically, there are two types of orbits that planets around a binary star system can have.

1. P-type (circumbinary)

• Planet orbits is around both stars. This is what all your planets do.
2. S-type (non-circumbinary)

• A planet orbits only one of the two stars.

This picture illustrates the difference better:

Since all your planets are P-type, let's focus on them. For a circumbinary planet, orbital stability is guaranteed only if the planet's distance from the stars is significantly greater than star-to-star distance.