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I have lately been pondering the possibility of life existing on a planet that does not have a sun. So far the little research I've done has suggested that the core would have to be hot enough, coupled with a much thicker atmosphere in order to hold an appropriate temperature to sustain life. Other than that I'm pretty stuck.

 

What would be the parameters of such a core and/or atmosphere?

 

Also, the biggest mystery to me is how plant life would be able to thrive, or if life could possibly thrive without plants at all (probably a topic for a different thread).

 

Any information would be much appreciated. Thank you!

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That's possible. The oceans would freeze over but some bacteria could exist in the liquid water at the bottom. Without the pull of the sun's mass the planet would fly off into deep space, and who knows where it would end up? Probably frozen deep in interstellar space or trapped by a black hole and eaten  whole......

 

No plants at all, I'm afraid, except for that advanced race.

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Welcome to hypography, Kmurphy! :) Please feel free to start a topic in the introductions forum to tell us something about yourself.

I have lately been pondering the possibility of life existing on a planet that does not have a sun. So far the little research I've done has suggested that the core would have to be hot enough, coupled with a much thicker atmosphere in order to hold an appropriate temperature to sustain life. Other than that I'm pretty stuck.

It may be that life on “Goldilocks zone” planets like Earth may less common than on sunless sub-brown dwarf planets. They are theorized to be about 100 time more numerous than stars, and geologically and thermally stable for several times the lifespan of a Sun-like star.

 

Though it’s conceivable that a sub-brow dwarf could have liquid water and Earth-like (ie DNA based) life, most of what I’ve read suggests they are too cold for that, so life would be based a non-water solvent like ethane. This 2011 Space.com article has a discussion of the possibility of life on sub-brown dwarfs.

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A recent talk I watched (recent is a relative term) given by a NASA researcher indicated that super earths with massive hydrogen envelopes could hold enough heat (in interstellar space) to have water oceans and chemosynthesis and hydrogen could power a ecosystem. I'm not sure about complex living things but I would bet that life will find a way... Possibly some sort of saturation unsaturation cycle driven by chemosynthesis?   

Edited by Moontanman
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A recent talk I watched (recent is a relative term) given by a NASA researcher indicated that super earths with massive hydrogen envelopes could hold enough heat (in interstellar space) to have water oceans and chemosynthesis and hydrogen could power a ecosystem. I'm not sure about complex living things but I would bet that life will find a way

I think this is becoming or has become the mainstream view among exobiologist astronomers.

 

Probability suggests that there are more people living on planets without stars – sub-brown dwarfs, rogue super-Earths, or perhaps even very low-power brown dwarfs with some H->He fusion happening in the cores – than people like us on planets around stars. To them, the idea that life is possible in the blistering stellar radiation environment we find so comfortable may be as outlandish as the idea that its possible in the cold, dark environment of a sunless world.

 

Another aspect of the fairly recent discovery that sub-stellar bodies are so common is that the distance between them is much less than the distance between stars, so spacecraft travel between them would be easier. Combined with these worlds being stable for much longer periods, and maybe less subject to catastrophes like giant meteorite impacts, starless world people might be more likely to be inter-stellar – or, I should say, inter-world – travelers than us sunlit world dwellers. On the other hand, these more massive worlds would be more difficult to escape from than smaller ones like Earth, so maybe not.

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I think this is becoming or has become the mainstream view among exobiologist astronomers.

 

Probability suggests that there are more people living on planets without stars – sub-brown dwarfs, rogue super-Earths, or perhaps even very low-power brown dwarfs with some H->He fusion happening in the cores – than people like us on planets around stars. To them, the idea that life is possible in the blistering stellar radiation environment we find so comfortable may be as outlandish as the idea that its possible in the cold, dark environment of a sunless world.

 

Another aspect of the fairly recent discovery that sub-stellar bodies are so common is that the distance between them is much less than the distance between stars, so spacecraft travel between them would be easier. Combined with these worlds being stable for much longer periods, and maybe less subject to catastrophes like giant meteorite impacts, starless world people might be more likely to be inter-stellar – or, I should say, inter-world – travelers than us sunlit world dwellers. On the other hand, these more massive worlds would be more difficult to escape from than smaller ones like Earth, so maybe not.

 

 

These planets would be more like mini neptunes than sub brown dwarfs if I understood the talk I watched. The surface would, with a little luck, consists of rocky land and oceans of water but with hydrogen envelopes of maybe (just a guess) 100s of bar. More likely they would be ocean worlds in my estimation but our tentative speculations seem to be kicked aside routinely by a more spectacular reality so often of late I am almost willing to consider almost anything...

 

So imagine a planet, 2x the size of the earth 16,000 miles in diameter, 8 times the mass of the earth, a huge dense atmospheric envelope of hydrogen and helium with reasonable traces of nitrogen , ammonia, CO2, methane, probably a significant amounts of noble gasses as well. 4 times the surface area of the earth, vast oceans and vast continents a constant cold driving rain, but only twice the gravitational pull of earth, a nuclear rocket of some type should be able to achieve escape velocity. It could have moons or even be one of many moons of a brown dwarf... the possibilities are staggering to think of...  

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