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14 votes
8 answers
3k views

How can life which cannot live on the surface of a planet naturally reach the supermajority of the planet's caves?

I want to create a setting focusing on a planet where nearly all complex macroscopic life lives underground, but I keep running into a problem: If a complex organism is adapted to cave life to such a ...
3 votes
3 answers
359 views

Biology of a Planet Sized Lifeform [closed]

This is also part of the sci-fi thing I'm working on, a planet sized lifeform. The planet sized biological creature belongs to the "Ancestral Elves" species, and is also the capital planet ...
13 votes
10 answers
4k views

How much time is needed to judge an Earth-like planet to be safe?

A colony ship has been sent to deep space to colonize an earth-like planet. Through astronomical spectroscopy, the atmospheric composition was found to be suitable for human life. But of course, ...
3 votes
1 answer
174 views

Could a biological organism power itself with electricity like a smartphone (or something similar)?

Imagine an alien world where there are are shallow lakes where electricity generating beings (like electric eels or whatever) would power many of the land dwelling creatures, including the dominant ...
2 votes
1 answer
114 views

Life in the core of a rocky planet

Background First of all, I’d like to state that I know the entire premise of this question is hypothetical and the life probably quite unlikely to form in the first place at best. Despite that, I’d ...
6 votes
1 answer
349 views

Alternate Biology/Xenoforming:Could the moon have a Chlorine atmosphere?

So I have this idea that a super advanced being travels across the galaxy and is terraforming/xenoforming every planet that CAN be modified for life, not just Carbon based Earthlike lifeforms but ...
13 votes
6 answers
3k views

Minimum amount of land a planet can have and still be habitable?

I read in a paper, posted by L.Dutch, that: It turns out that water worlds may be some of the worst places to look for living things. One study presented at the meeting shows how a planet covered in ...
6 votes
3 answers
382 views

Plausibility of life emerging and evolving on gas giant moons?

I have been working on the setting for a hard speculative biology/evolution project that for now will simply be referred to as the Gemini Project, and the main issue I've been having is whether or not ...
2 votes
3 answers
225 views

Could a planet 2 times the mass of earth have floating organisms in its skies

Can a planet 2 times the mass of earth have floating animals in its skys? I watched the netflix documentary series ailen world's and one of the exoplanets atlas was high gravity but was very dense so ...
1 vote
0 answers
198 views

What would life be like that uses liquid nitrogen as a solvent instead of water? [closed]

I'm working on a worldbuilding project and want to have an intelligent species from a planet where liquid nitrogen is the dominant solvent, not water. I plan on building the planet backwards from here ...
15 votes
1 answer
2k views

On a planet with larger gravity, would aquatic creatures be larger or smaller?

It is somewhat common knowledge in the worldbuilding community that larger planets leads to smaller land creatures, because larger planets means more gravity gets bigger and that makes it harder to ...
10 votes
2 answers
337 views

A planet with acid rains but its atmosphere is breathable

I am trying to create a planet that rains acid, and that has acidic oceans of water, but a breathable nitrogen-oxygen atmosphere. This planet has native lifeforms that have evolved to withstand these ...
6 votes
7 answers
1k views

How did the vast nexus of hollows, caves and a thriving underworld on this alien planet come to be?

I had a unique idea for an alien planet. The surface would be snow-capped mountains and glacial fields, it's cold and essentially devoid of most life. But just underneath the towering mountains ...
10 votes
8 answers
4k views

Life underneath a blue star

Blue stars are notorious for burning too bright and living too briefly for life to develop around them. But is there some way that life could survive long enough to reach the sentience stage? I'm ...
3 votes
3 answers
293 views

If we accidentally spread microorganisms to other planets in our solar system, could they evolve into complex life?

Is the following story plausible: a spacecraft transports microorganisms from Earth to another planet or moon in our solar system. Those microorganisms survive, and eventually, evolve into complex ...
8 votes
3 answers
272 views

Surviving a dark hycean world

A dark hycean world is supposed to be a hot water world with a thick atmosphere around a red dwarf star. This means it's tidally locked with one side forever facing the sun and the other forever ...
4 votes
3 answers
443 views

How Can a High Gravity Planet Have a Magnetic Field

We all like life forms from high gravity planets, it’s a popular Sci fi trope and one that I love to play around with. It’s fascinating to try and designs creatures for an environment that would ...
2 votes
2 answers
200 views

Electricity-powered life on an ice planet?

I imagine that in a nearly Earth-sized ice planet with an atmosphere similar to that of earth, life has been able to proliferate. It first formed in the oceans below the ice, which are warm enough for ...
6 votes
2 answers
188 views

How can I get mostly-hydrogen-sulfide seas (with lifeforms in them)?

The lifeforms don't have to use hydrogen sulfide as a solvent. Maybe they've got an internal water-ammonia eutectic mixture or something; anyway, it doesn't matter. The point is, I want an ocean of ...
2 votes
2 answers
373 views

How colorful would plants and animals in a habitable planet orbiting a F main sequence star would be?

F main sequence stars are hotter and brighter than the Sun and therefore they emit more UV radiation than sun-like stars. Many scientists think that complex life could develop in planets orbiting such ...
4 votes
1 answer
262 views

What kind of world could produce polyoxometallate life?

There has been some cool work in synthetic life to produce cells based on polyoxometalate ions, certain metal oxide complexes have been shown to have autocatalytic behavior, and heteropolymetalate ...
9 votes
1 answer
2k views

Could a planet with 0.9 Surface gravity retain this atmosphere?

I have a planet with a surface gravity of 0.9 times that of Earth, and an escape velocity of 11.3 km/s, and a temperature like Earth's. My question is if it could retain a breathable atmosphere (for ...
4 votes
2 answers
237 views

How would plants obtain helium on an earth-like planet?

My question is how would plants obtain helium in land?, mainly for floating in a high surface pressure atmosphere (maybe around 1.5 atm?), or at least its seeds or tiny parts of them, also it is ...
4 votes
2 answers
295 views

Low G vs High G planets and floating species

So, i want to make a planet with these requirements: A higher surface pressure than earth, and an atmosphere that could last long enough for intelligent life to appear. (If possible), medium or large ...
4 votes
6 answers
628 views

How to make an Old Solar System planet Venus scientifically possible?

The "Old Solar System" is our solar system as described in many space operas and planetary romances written before the space age. https://www.solarsystemheritage.com/ In stories in the Old ...
1 vote
2 answers
72 views

Life present on earth-like habitable exo-planet

Scientists are looking for an earth-like habitable exo planet. If an exo planet is earth-like (in terms of gravity, atmosphere, light, water etc.), then it must have gone through an evolution process (...
2 votes
5 answers
272 views

Are there things that can make natural lifespan in other planets inherently longer?

How would things like gravity, air composition and density affect the lifespan of the biological protein based life that inhabits the planet, or would they have any significant effect at all? Honestly ...
6 votes
2 answers
2k views

Methane-Breathing Animal?

In my story, Saturn’s moon Titan’s methane lakes are inhabited by microorganisms that photosynthesize, converting hydrogen into methane (A process thought possible on Titan after some study). This ...
1 vote
4 answers
2k views

Is an almost entirely water-based planet stable enough to stay as a planet for long enough for complex life to form?

Imagine an earth mass that consists purely and entirely of water that orbits a star similar to ours at a similar orbital distance to Mars(or whatever distance would be sufficient for the planet to ...
6 votes
3 answers
496 views

Is this Martian creature plausible?

I am thinking of writing a story about a Martian civilization. It might involve humans, but, I think it will be more interesting if there are creatures adapted to the Martian lifestyle as well. So, ...
1 vote
2 answers
142 views

Traits of an intelligent & civilized species that lives under a red dwarf star?

More details -- their planet is very bigger than Earth, has stronger gravity than Earth's, it has 2 moons, it's not tidally locked, and they're supposed to have evolved from social obligate carnivore ...
8 votes
4 answers
479 views

NASA discovery: 1 star, 7 planets, multiple in habitable zone. How would this affect life on the planets?

I have left a link to the NASA video in case you are not to sure what I am referring to or to get a better picture of what I am talking about. https://www.youtube.com/watch?v=bnKFaAS30X8 With that ...
-2 votes
1 answer
90 views

Alternative biology/Xenoforming 3:any ideas how to xenoform Mars? [closed]

So i have an idea of an super advanced being that travels around the galaxy and spreads life on every planet that has any potential for it.By "life"i do not mean only "Carbon based"...
8 votes
9 answers
2k views

Is a planet sized creature possible?

Now, I have started working on a game called In The Flesh, and I have decided to use this site to work on it. The Game Itself In any case, the main idea of In The Flesh is that it's a sci-fi ...
1 vote
1 answer
380 views

Changes to water worlds to make them habitable

What changes/additions/deletions, large or small, minimum handwavium allowed, would be needed to make suspected water covered exo-planets such as Gliese 1214 b, Kepler-22b, Kepler-62e, and Kepler-62f, ...
6 votes
1 answer
244 views

Oceans of breathable liquid

I want to create a locale (hopefully a whole planet?), where the ocean is breathable. I was looking at perfluorocarbons, so the liquid part is at least possible(?) Is there any way to create a world ...
2 votes
1 answer
166 views

What color would plants be on a hot spring planet? [duplicate]

I had an idea for an alien world I want to set a story on and if this question proves popular I might ask other questions regarding this world. The world in question is an earth like moon orbiting a ...
16 votes
13 answers
2k views

How did aliens on a habitable planet hide themselves during the recon and scouting stage by human colonists?

We've found a habitable planet orbiting a red dwarf star some light years away and conditions are Earth-like enough that a colonization project was initiated. Before any humans landed on the planet, a ...
4 votes
2 answers
338 views

A bacterial organism that survives on the surface of Venus

Yes, you read the title right. Naturally this cannot be DNA/RNA based, the highest temperature organisms have survived as we know it is 122 degrees celsius and Venus surface is 4 times hotter on ...
2 votes
1 answer
156 views

What would Martian Life be like? [closed]

Basically what I'm asking is how would hypothetical life be able to survive on Mars? Would they need to be created from scratch in some effort to make life on seemingly uninhabitable worlds or ...
3 votes
4 answers
209 views

High energy, low temperature?

Alien spacecraft have entered orbit around Earth. They have launched a few probes for closer observations, but made no attempt to land. Figuring out meaningful communication is an ongoing process, but ...
3 votes
4 answers
110 views

Earth-sized Moon with Host Planet launched from Star System

Could a planet with the size and characteristics of the Earth orbit a gas giant and would the earth-like moon be able to maintain its orbit if the gas giant went rogue and was launched from its host ...
5 votes
2 answers
480 views

Would a life-bearing Earth-like world with 3g average gravity produce more or fewer flying creatures than Earth?

On one hand, heavier gravity would make flying more difficult, owing to greater weight restrictions on the flying creatures' bodies. On the other hand, the greater density of the atmosphere on our ...
5 votes
3 answers
203 views

Can a perpetually darkening atmosphere exist and yet still allow life to evolve?

I am creating a science fiction worldbuilding project, in which humanity has colonised distant exoplanets. One such planet is a Venus-like planet in the sense that it has a perpetual cloud cover, ...
1 vote
1 answer
108 views

Lifespan of Plutonians [closed]

Honestly, I think my questions about a fictional Pluto are by far the interesting to me, so I have another question. Now that I’ve got my humanoids pinned down, and what protects them from the cold, ...
9 votes
2 answers
2k views

How would oceans of supercritical CO2 on Venus-like exoplanets look like/behave?

Carbon dioxide turns supercritical above a pressure of 73 atm and 304.25 K (31.10 °C). The surface of Venus fullfils these conditions. The density of the air at the surface is 67 kg/m3, which is 6....
4 votes
2 answers
894 views

Adaptations for an ice planet?

My planet is a frozen world. Roughly the size of earth and in a perpetual ice age. The planet has very cold temperatures at night and during the day its surface becomes very bright. The intense solar ...
6 votes
5 answers
527 views

Would complex life evolve on this planet, and could humans survive on it without much outside help?

Okay, as an extension of my previous question, I'm just going to lay bare all the details I've written down about this planet (including corrections from my last question), and ask the big question ...
6 votes
4 answers
714 views

Cool way to see through fog and darkness

My planet is frequently set with thick fog. What is the best way to have its residents see accurately? One species called Hell Fires fall from the sky, landing on top of prey and killing it. How ...
10 votes
4 answers
5k views

Would it be possible for an Earth-like planet to have multiple moons with diverse biomes capable of supporting life?

Thanks for taking a moment to help me understand the feasibility of this scenario. Essentially, what I am looking at is an Earth-like world that would be between 1.3x and 1.6x the mass of our own ...