Note: Please try not to overcomplicate it for me. I might sound mature, but I'm actually a minor and as much as I like complex wording, I want it to be understandable.

Hey! Basically, I'm drafting up an idea of one of the few humanoid species in the intergalactic governing body that I've created. This is for a book, but I just want to draft my species down before I write them into my book. As such, I wanted to make a hypothetical scenario where the only life found in the galaxy around a brown dwarf is this species.

From an evolutionary standpoint, I've incorporated larger eyes to allow for vision of said 'sun'. The planet is also tidally locked. Would they be able to survive on a planet orbiting a brown dwarf? The geography is highly mountainous, so the air is cooler - I know that much. This is just a hypothetical scenario whilst I find out more about the stuff I need to know.

  • $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Jan 26, 2023 at 14:41
  • $\begingroup$ For beginning your researches, perhaps take advantage of the search facility at the top of the page. A previous question regarding Tidally locked planet, extent of habitable twilight zone? might start you off. Please also take our tour and refer to the help center for our guidelines. $\endgroup$ Jan 26, 2023 at 14:45
  • $\begingroup$ @aPrimevalWorld, welcome to Worldbuilding. This Stack has a number of rules that will be important to understand as you continue to ask questions. Please carefully read through the tour and the following two Help Center pages: help center and help center. Also, note two more things. (a) You're allowed only one question per post (you only have one here, great!) and (b) questions must reflect specific problems ("what should I take into consideration" is too broad, but we'll let it slide as you're a new user). Thanks for joining us! $\endgroup$
    – JBH
    Jan 26, 2023 at 15:42
  • $\begingroup$ Ah, my apologies! I'm still learning the ropes and all, so I appreciate letting it slide. Might take me a moment to get into routine with this because I'm not used to being direct per se, but I was saying that because I really didn't know what I wanted out of this. I sometimes say things like that when I'm unsure on how to ask what I want or if there are multiple things - nonetheless, you are right in saying I probably should work on that. Regardless, thank you for all the help and I will defo check out the tour and also the help pages! $\endgroup$ Jan 26, 2023 at 15:47
  • 1
    $\begingroup$ I'll do all of those things immediately, or at least as soon as I can when I've got physio and hospital stuff to do like any second. $\endgroup$ Jan 26, 2023 at 15:49

2 Answers 2


Summer night world.

Here is a recycled answer of mine from here:

Endless global night.. but an agreeable climate, how come?

Brown dwarf emissions are almost all infrared. They do not put out much visible light and what they do is red.


Here are compared the emission spectra from 2 different brown dwarfs with that of the sun. Brown dwarfs are from

https://www.eso.org/public/usa/images/eso9709b/?lang Sun is from wikipedia.

Note the brown dwarfs are in angstroms and the sun in nm. Divide angstroms by 10 to get nm.


Red light is 700 nm / 7000 A and almost all of the emission from the brown dwarfs are longer than that - invisible infrared.

Thus orbiting a brown dwarf you could get plenty of heat but very little light. This is your warm night world. The little bit of visible red light put out by the star makes the days red.

As regards the nuclear fire going out at 10 million years - true. But even though it does not shine, the brown dwarf stays hot and continues to radiate in the infrared. Your tidally locked planet is very close to its hot dwarf. It can stay warm and also "illuminated" by both the hot brown dwarf and also the dusty ring around the dwarf. That ring is hot too and secondarily emits infrared radiation for your planet.

-- The dark side of your planet will be colder. But maybe not that much colder - I could imagine the warm winds on the summer night world carry heat around the globe.

-- Seeing infrared is definitely possible. This world will look dark to us but not necessarily to its inhabitants.

/ a hypothetical scenario where the only life found in the galaxy around a brown dwarf is this species/

Galaxy? Those are big. Maybe you mean only intelligent life? I figure there must be some other form of life on their planet because they will get hungry otherwise. Some sort of autotroph?


‘fraid not.

The habitable zone of a brown dwarf is extremely short-lived. Since brown dwarfs cool rapidly, the habitable zone is continually shrinking. Your planet would have at best 10 million years of habitability before freezing. You might get some ephemeral, single-celled life forms for a few million years, but before long the planet’s surface will be uninhabitable.

If I were you, I’d consider moving this ecology beneath the sea; once the planet freezes, life could continue to thrive in a subsurface ocean, generated by tidal flexing from the brown dwarf “sun”. An ecology like this could exist for billions of years as long as the planet keeps orbiting its star, so you could get all kinds of complex life forms after a while.

As for surface life? Nope. Sorry, there simply isn’t time for anything beyond the level of bacteria to evolve in the timespan described above.

  • $\begingroup$ Alright then! Thanks for the help, but do you have any suggestions of other star that I could use instead? Ideally I want life to be sustainable, but also for the species to still be able to have big eyes - basically, minimal light being reflected to the planet. $\endgroup$ Jan 26, 2023 at 15:41
  • $\begingroup$ Real Life cannot be an overriding limitation on any question unless specifically requested. While this answer explains what the challenges are for life on a planet orbiting a brown dwarf, it fails to answer the question of how life could be adapted to make it work. (e.g., "it must evolve faster....") $\endgroup$
    – JBH
    Jan 26, 2023 at 15:44

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .