In my story, I have an superhabitable exomoon that is tidally locked to a gas giant (a planet similar to Saturn with the rings, but slightly smaller). This gas giant is in an s-type orbit of a binary star system. Right now I am planning to have the gas giant orbit a red dwarf star while the other star is a similar type to our sun. I was wondering how seasons would work on this moon, or resources to figure out seasons as well as the day/night cycle. I know that it depends on the rotation and axis but the math tends to confuse me.

Thank you for the help!

  • $\begingroup$ I feel you'd get better answers if you stated what you wanted, and asked how it could be achieved. As it is, the question is so under-constrained that answers can't help but be vague and handwavy and built under a different set of assumptions for each answerer. $\endgroup$ Apr 5 at 18:23

2 Answers 2


Understand that without concrete data on the system, all I can give you are rough guidelines. It might be worth building the system in a simulator like universe sandbox.

Being tidally locked to a gas giants means that orbital period is equivalent to day-length. The atmosphere will keep the temperature rather moderate around the planet. Unless the moon has a high inclination or the gas giants an eccentric orbit, this should be it. No significant seasons here. If not, well that's something a simulation can deal with. Anything from regular freeze or fryovers to a polar equator and poles with extreme winters and summers are in the cards.

The influence of the G-class depends on its distance and the eccentricity of the orbits. It might do absolutely nothing (in which case the red dwarf would probably be insufficient to keep the world habitable), keep the planet's temperature moderate if it keeps a moderate distance or it could fry and freeze the world. The thing to remember about its influence is that it will spend most of its time far away from the red dwarf (near apoapsis).


Your system conditions seem pretty violent,

i dont think you can have a s type orbit , becose once you leave the orbit of the first star your planet is continuing a inertial movement beyng atracted from the second star ..

how to explain.. imagine trying to spin a rope with a weyght at one end , once you let it go , it wil stray away , and other person has the imposible task of catching it, so an s-type ofbit is kind of unstable orbit,

in your context your exomoon is orbiting its gaseos planet and influenced by your double star :>> seasons i dont think you cant have becouse violent conditions of the gravity exerted form your dual star system and your gaseous star influence ,

your storry must be altetred a bit, consider the double star is in the center of the system conected in a gravitational push with each other

your gaseos planet has a eliptical orbit at a distance of 20 diametres of its first star.

and now your gaseos planet is further away, and your exomoon isnt much influenced from the double stars form center of the system , so then i think that stil the conditions are to be less harsh on the moon's surface and waters so your only inhabitable options are more forgivable. still i think your living options should be on the surface and under.

NOW ! you can decide how many seasons you can have 2 or 4 ..

please feed back me..

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    $\begingroup$ I think you fundamentally misunderstood what a n s-type orbit is. It means that the planet orbits only one primary. A p-type would mean that the planet orbits the barycenter of two or more primaries. What you describe is a chaotic orbit. $\endgroup$ Apr 4 at 7:57

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