<p>Could a binary star system have an earth-like planet orbiting star A, a second earth-like planet orbiting star B, AND a third earth-like planet in a stable circumbinary orbit? Or does the space that is required between the two stars to allow for stable habitable zone orbits for the first two planets eliminate the possibility of the third planet being both habitable and in a stable circumbinary orbit?</p>

CC BY-SA 4.0
2019-04-12T06:52:31.803Z
Interesting question. I think if you had two stars of significantly different brightnesses, you *might* get a habitable zone around the dimmer one and another circumbinary one. I don't think you'd be able to have three separate habitable zones.
Ingolifs
CC BY-SA 4.0
2019-04-12T18:49:01.147Z
"habitable" gets close to World-Building.SE --  development of life on planet 3 vs. folks from planet 1 or 2 setting up shop there and staying underground during the "dark" periods of the orbit.  But I suspect Ingolifs is correct that the orbital mechanics will require planet 3 to be significantly farther from both stars "most" of the time.
Carl Witthoft
CC BY-SA 4.0
2019-04-12T23:23:27.583Z
@CarlWitthoft by habitable I merely meant in a goldilocks zone orbit. I'm asking if it would be scientifically possible to have three separate goldilocks zones in a binary system- one around each star, and one circumbinary. I agree with you in guessing that this probably isn't possible, but I'm really curious to know if I'm wrong.
MarielS
<orbit><earth-like-planet><habitable-zone>
Are circumbinary and noncircumbinary habitable zones mutually exclusive?
MarielS
# Are circumbinary and noncircumbinary habitable zones mutually exclusive?

(Asked by: username_0 on 2019-04-12)

Could a binary star system have an earth-like planet orbiting star A, a second earth-like planet orbiting star B, AND a third earth-like planet in a stable circumbinary orbit? Or does the space that is required between the two stars to allow for stable habitable zone orbits for the first two planets eliminate the possibility of the third planet being both habitable and in a stable circumbinary orbit?

**Tags:** orbit, earth-like-planet, habitable-zone

> **Comments:**
> **username_1**: Interesting question. I think if you had two stars of significantly different brightnesses, you *might* get a habitable zone around the dimmer one and another circumbinary one. I don't think you'd be able to have three separate habitable zones.  
> **username_2**: "habitable" gets close to World-Building.SE --  development of life on planet 3 vs. folks from planet 1 or 2 setting up shop there and staying underground during the "dark" periods of the orbit.  But I suspect username_1 is correct that the orbital mechanics will require planet 3 to be significantly farther from both stars "most" of the time.  
> **username_0**: @CarlWitthoft by habitable I merely meant in a goldilocks zone orbit. I'm asking if it would be scientifically possible to have three separate goldilocks zones in a binary system- one around each star, and one circumbinary. I agree with you in guessing that this probably isn't possible, but I'm really curious to know if I'm wrong.  

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## 0 answers

