The moons of rogue planets could have liquid surface water and thick atmospheres. They could be habitable.

The moons of rogue planets could have liquid surface water and thick atmospheres. They could be habitable.


Imagine the cosmic horror of being a sentient lifeform on a planet like that. * Never ending nightfall * All energy moves in one direction only: down to up. * A giant slightly glowing gas giant dominating the sky on one side of the tidal lock nothing but stars on the other. * No seasons. * unpredictable jets of super heated water burst out of continent sized ice plains. What would the aquatic life be life? Would it develop energy pumps based on heat and salinity? Would predators and prey be a war against gravity vs energy? Alpha predators in cold climates strike down on abundant prey in the warm depths? The bottom of unimaginably deep waters superheated under massive predators feasted upon by scavengers?


These things would be normal for them I guess.


"Wait your temperate changes every couple of months? What the hell? Do you have to buy like multiple types of clothing? What about harvesting? How do you grow enough food with such short growing seasons?"


Wait you have to adapt to live in both day AND night?


Get this, we typically go unconscious when the night comes and only do things during the day!


What the hell even is day though? There is nothing to illuminate the moon and if its tidal locked nothing to indicate passage of a fixed time


They would probably use the movement of stars in the sky as they orbit the gas giant to tell time.


Would they even have evolved eyes in a world with no sunlight?


"You have UV radiation coming from the sky half of the time, cutting your DNA to ribbons, significantly shortening you life?"


"The source of which is a vast unshielded nuclear reactor that will destroy your eyes if you so much as look at it?"


"Also, what are eyes?"


"Yes, although if we also don't get SOME of it, that also significantly shortens our lives!


We are the universe's Chicagoans. Behold our surface water as it gradually goes thru all three phases without our help or control!


Just another day at the office for sure


Your office is in between layers of kilometers of ice powered by Stirling engines. You and your coworker swap jokes about rednecks on the surface and how backwards they are before HR writes you up.


> rednecks This term would be funny - since it usually refers to those who are exposed to too much sun... but no sunlight on their surface, so... we'd need to come up with a new hypothetical alien slur :D


Rad necks, those exposed to the high radiation emitted by being so close to a gas giant


I thought Jupiter shot out x-rays


x-rays are a form of radiation


Yeah so as the other person said. They would be rad necks. Haha. I am liking the metal image of like octopuses talking down about the surface octopuses. If you think digging in ice for hours to catch a fish is fun, you might be a rad neck. If you pray to the big orb in the sky instead of the down orb you might be a rad neck.


Ice-moon holy war cage match: Up-Orb vs. Down-Orb edition!


If sentient life ever evolved in such an environment, they would consider it impossible for life to evolve anywhere near those firey balls of superheated plasma they see through their telescopes.


>No seasons. That doesn't even sound like a bad thing - you have to evolve to a single temperature/type of weather instead of having to adapt to different ones.


Hard to say. Dynamism presents challenges, but also opportunities. Life might evolve on a very static world, but I wouldn’t be surprised if it stayed simple. Something just becomes extremely well optimized for the current environment and there is no reason to ever change.


Depends. The conditions created by life itself might in certain circumstances provide a changing and dynamic environment that eventually leads to complex life. It might even be that a steady equilibrium is inherently unstable. After all, if you have ten, twenty, thirty billion years for random mutation (or analogous random elements) to find a thus-far unbeatable exploit in the ecology of your world then chances are it's going to come along eventually and cause a whole slew of knock-on effects. All it takes is for life to find itself in a position such that at least one clade is forced down the path of increasing intelligence.


depends, there's a hump you need to overcome for that to actually work out. Without fire your tech tree is basically truncated to extreme biomanipulation the hard way (through breeding) and it could take longer than your race can exist to get anywhere with that. Look at cephalapods, they're highly social and intelligent but without external tool use there isn't a pressure to go down that exact route of sociocultural development.


Complex life can have advantages in static environments as well as dynamic ones. Life is always competitive.


Would they sleep? No day and night cycle.


Not all animals sleep during either day or night. Some sleep in random bursts whenever possible, so I assume this wouldn't be a problem.


My favorite is how dolphins only shut down half of their brain when sleeping, alternating between the two halves. I pretty much did this same thing while working shitty retail jobs in high school.


https://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep Literally sleeping with one eye open.


I really wonder how that would work... Considering humans, one half is pretty analytic and cautious while one is spontaneous and creative right? I just imagine the dolphins acting so differently in the two states


I read on reddit actually that humans sleep similarly when sleeping somewhere you haven’t slept before. Let me find the link


They probably would be horrified we have to basically shut off for 6-8 hours a day.


> you have to evolve to a single temperature/type of weather It’s true, just ask Floridians.


You have never been to Florida, clearly


Would they even be able to make telescopes under water? I feel like the technology peak for underwater species is pretty low without things like fire.


The article suggests that there would be some surface water on a theoretical rogue moon, but it wouldn’t be a water world. So in theory there could be land-based life just like here. It does seem unlikely that ocean-based life would ever develop much technology though. Not impossible, but fire is a pretty important step.


This. Any time people speculate on alien life, they limit themselves to the familiar. Extremophiles were a pretty big deal in the science news cycle for the same reasons. People wonder what life would look like assuming it started similarly to here. My guess is 'genesis' can happen in ways we haven't even speculated on yet. Also, I suspect arrogance is a naturally emergent trait in intelligent species.


Why? If we conceive of life on their satellite do you think so little of their imagination that they could not theorize life on ours?


To be entirely fair, it took us quite a while to get to that point.


The time frame seems rather irrelevant though. The statement above is rather definitive, which seems rather odd.


I think it took us no more time than it took to know about the planet


Yeah, like growing up in brazil


Just what I was thinking. I mean they can't really compare if they don't know.


Doug Adams summed this up quite well in the style only he can: > This is rather as if you imagine a puddle waking up one morning and thinking, “This is an interesting world I find myself in—an interesting hole I find myself in—fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!” The puddle knows no other world. Everything in the puddle’s world appears to be made for it.


Imagine the cosmic horror of living under the dominion of a star so close it irradiates and burns the surface at regular intervals with millions of apocalyptic-scale meteors whirling about within only a few AU. The peaceful night sky fade and the stars go dark as the GREAT STAR rises, bright enough to burn the eyes of creatures on the surface, hot enough to start fires with only a small amount of refraction from a lens. Winds stirred up by the constant swirling of heat vortex rage at hundreds of kilometers an hour every day all day in jet streams that carry dust and water across the entire planet. Now and again the bright tail of a comet streaks across the sky, always pointing to the Great Star. There's no telling when such a cosmic neighbor might pay too close a visit, but over a long enough time scale it's a virtual certainty.


I gotta admit you just made Earth sound metal as heck.


Beneath your feet is a 2000-mile ball of ragingly hot iron and nickel, ten thousand degrees, and all that keeps you from falling into it is some dirt.


About a fifth of our atmosphere is one of the most corrosive elements.


And we need it en masse to survive...


You're only ever a few minutes away from dying, and breathing just resets the counter.


We drink molten ice. We're basically gorons.


I don't think metal goes down as low as heck


Also the floor explodes intermittently into clouds of liquid rock.


And hundreds of millions of gallons of water can just fall out of the sky anytime, anywhere.


And then add the horror of dealing with the cable company!


They told me it would be Comcastic!


Also the atmosphere is made of highly corrosive oxygen. Electric discharges from huge storm give the ignition sparks for massive fires. The winds get so bad that they strip some places of vegetation. Plus there are some freakish lifeforms surviving all that nonsense and they are searching for you.


> freakish life forms searching for you Australia has an interstellar reputation?


That's why I never leave my house tbh


You should write sci-fi novels.


I write historical fiction and non-fiction


If you evolve in such environments it would be normal to you, and you will feel the horror of scorching heat when your world passes by a giant white demonic fireball known as a star.




"cycles of *months* where the normal food supply is unavailable, traveling to other regions which have no water entirely and are blasted by immense amounts of photonic energy, alternating high-salinity or low-salinity bodies of water, atmospheric conditions which vary greatly on a daily basis based on a number of micro-geological factors relative to your location..."


Another good point. On our rogue moon latitude and longitude don't matter only your distance from the next patch of melted surface ice. Your near vacuum (maybe some water vapor) surface would be literally ice smooth. Maybe with the occassion Everest sized iceberg on the plane from frozen eruptions sliding on the surface over eons. Like Pluto. I think the vast Europe ocean would have salinity variations. We see them in the southern sea which is a closest analog to it. The core heat causes rivers and thermoclines. Patches of deep salt form a protective layer preserving itself, much like we see when caustic is rapidly added to an acid solution (any oceanographic people want to correct me?). Drifting zones of salts the size of our cities buoyed on the ocean rivers. Criters inside and out running chemical pumps.


Latitude and longitude might matter. Presumably the moon’s rotation would be tidally locked. The portions of the moon nearest to and furthest from the host planet may experience the most tidal heating, while the mid-distance parts of the moon may experience less tidal heating? One would need to work through the details to be sure. It might even be the other way around. But, there will potentially be differences in heating, based on location. Edit: on second thought, if the moon is rotationally locked, that eliminates tidal heating… unless the orbit has high eccentricity…. Anyway, it’s not as simple as I initially thought, but I still think that tidal heating will not be uniform over the surface of the planet. Thus, location will matter.


I admit I was thinking of the ice surface top. I just assumed that if they had a few kilometer thick ice sheet that it would even out. You might be right, maybe inside near the bottom it would matter?


The article summary here didn't say anything about vacuum. If there's enough tidal heating, there might be enough to keep an atmosphere warm. But that would be a lot of heating & I wonder if that would just dissipate the conditions that would produce it (circularize the orbit, stop rotating, whatever).


Ok let's play. On our ice world down is always warm and up is always cold. Up areas want to move down because of gravity and lower areas want to move up to correct pressure. I guess that would give us a cyclical wind pattern. The low pressure makes water unlikely so sublimation is the norm. Dang someone smarter than me should figure this out.


Critters raised on a world where up is cold and down is hot can't imagine a world where heat comes from both angles and various. They picture us eking out an existence in a narrow habitable zone between our heat engines. A ringworld baked unreliable by two engines. They wouldn't be too wrong.


"Imagine, about half the time a giant flaming ball is visible and casts its visible, burning, light rays down on you" - Rogue planet moon fish, probably


I dunno, if a race developed on one of these they’d look at Earth and wonder about the cosmic horror of being a sentient lifeform on a planet constantly bathed in ionizing radiation and plasma winds of a constantly exploding fireball that could wipe out everything with an ill timed fart, the chaos of tides and seasons, unpredictable jets of super heated molten rock bursting out of enormous plates of a shattered and unstable crust, surrounded by a cloud of rocks just waiting for the wrong graviton purtabation to rain extinction.


Wait would they know about our core? I thought we only have an active core because of uranium. Would they instead think of us as living on a planet like Mars?


I thought the Insight lander recently detected the first known Marsquakes. Perhaps it's more geologically active than we assumed? Something must be driving that process, it's a lot of energy to measure.


I suspect you'd have vision in the infrared range, and would be just fine. Just because it's not what we call "visibile light" doesn't mean something else couldn't evolve to see it.


This. Both IR and sonar would be just fine.


But what would you see with infared? I am not an expert on this stuff but don't infrared hunters hunt warm blooded critters? Would there be warm blood critters on an ocean moon?


>No seasons. Imagine the cosmic horror of... California


Excuse me? California has seasons! It's got normal, fire and mud slide.


And apocalyptic drizzle on the freeways.


I’ll read that sci fi novel.


I have a book you may be interested in then. Seeker by Jack McDevitt. Its a great read by a nebula award winning author.


Have you read *Nightfall* or *The Three Body Problem*?


I’ve read nightfall (which is the opposite) and three body problem is in my list. Pitch black is related too.


Energy moving only in one direction, what do you mean by that?


In our world we live on a sea of molten iron that pushes energy upwards and face a star shooting energy at us downwards. On their world effectively all energy comes from the tidal forces in the core and moves to cold space. We are a ring world between these two sources. Nearly all life that exists is in the narrow band between the two at sea-level.


A rogue planet within a galaxy certainly wouldn't be as chilly as you describe it since it would travel through an unpredictable interstellar medium that occasionally reaches a quite extreme temperature. On a rogue planet that has been catapulted out of it's galaxy there wouldn't be any nightsky visible with our eyes since all stars would be too far away. Without photoreception in simple life, why should eyes evolve at all ? It's much more likely it would develop infrared sight instead.


>A rogue planet within a galaxy certainly wouldn't be as chilly as you describe it since it would travel through an unpredictable interstellar medium that occasionally reaches a quite extreme temperature. Wait, really? Mind expanding on that? Sounds pretty awesome - I was under the impression that the interstellar medium consists mostly of vacuum near (but not at) absolute zero, and that objects such as nebulas are exceedingly rare to the point of being virtually impossible to hit from the perspective of a rogue planet?


Yeah I imagine thermal imaging and/or echolocation would be as ubiquitous as eyes are on earth. A planet populated by things just screeching.


Imagine the horror of being a sentient life form on earth. • you get used to living in day, then darkness comes. • energy moving in all directions • a tiny moon in the sky, gives you nearly no light at night • the weather doesn’t make its mind up and you live in areas were it could freeze them a month later it’s super hot •volcanoes, earthquakes, tornadoes, and hurricanes could hit at any moment. It’s all about what you have adapted to live with.


I mean animals on our planet see in the dark. Itd be riddick pitch black, theyd all have different visiobs.


I was thinking more along the lines of the colony that ends up stuck on one of these moons, potential wildlife and natural disasters aside. Imagine you finally reach one of these moons, you get setup, you have a home of sorts for your colony, things are going well. Maybe a few Earth years, maybe a few decades, maybe a few generations go by and someone realizes there's not as many resources here that can be used to build more ships or replace the fuel for the original one people arrived on. Now you're stuck in this place of seemingly eternal night until either everyone dies. Staring at the void, feeling so hopeless, just waiting to die go blissfully insane until the final butter end stranded on a place so far from home. The last thing humanity will hear from your colony is that one last SOS or goodbye broadcast out into space for anyone to pick up.


Sounds like Reading town center! xD


You should write sci-fi novels.


Thanks. I have put out a few short stories.


I mean, cosmic horror to us, sure, but to any life form on these moons, it would be totally normal. It would be equally horrific to them to have a blazing star above their heads


An entire scifi novel has been written about this as part of an even larger mini panspermia in a similar setting. https://en.wikipedia.org/wiki/Ocean_Under_the_Ice


>What’s interesting about these examples [Ganymede and Enceladus] is that the presence liquid water on these moons is due not to the heat of the Sun, but rather to thermal heating due to the gravitational tug of their planet. That is crazy, I always assumed the heat on those moons was geothermal.


It is geothermal, but geothermal is not an energy source. Where did the geothermal energy come from? The centers of planets don't get hot simply by being the center of planets. The tidal tug on a planet results in friction, heating the core, which then can be harvested as geothermal energy.


> heating the core As a minor point. It heats where the dissipation of tidal energy takes place. This could be the core, but could be in other places like a liquid ocean.


Yes, true. Anything affected by tidal forces will be heated up. I was just talking about it in the context of geothermal, not tidal forces generally.


It certainly won’t be at the core where tidal energy dissipation and heating occur. It will be where there is flexing of materials, which will happen most strongly far from the moon’s center of mass.


The strength is not the key thing. The source of dissipation is. You can have regions of weak forcing but high dissipation which result in more heating than a region with high forcing and weak dissipation. For a terrestrial planet with a liquid ocean then the dissipation is likely to be highest in the oceans. For a Sun-like star with a fully radiative core then the dissipation is likely highest at the geometrical centre of the radiative region.


According [to wikipedia](https://en.wikipedia.org/wiki/Geothermal_energy): "The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials (in currently uncertain but possibly roughly equal proportions)."


These moons are too small for that to be a significant source of heat, so geothermal energy on them relies on other sources, primarily tidal


Yes, but that’s not how tidal heating originates, and tidal heating is what allows an exomoon around a free-floating planet to be warm enough to have liquid water.


But the person they're replying to said this: >The centers of planets don't get hot simply by being the center of planets.


> geothermal is not an energy source Not entirely true. Much of geothermal energy is left over from when the solar system formed and was much hotter, but there are also a lot of radioactive isotopes down there generating new heat. You are right that both the leftover ambient heat and radioactive isotopes will eventually run out. And the heat generated by tidal forces stretching and squashing gas giant moons _is_ generated new each orbit, That said, the flexing does sap energy from the overall orbital system, and that will eventually decay too. Entropy always wins in the end.


The radioactive isotopes in Earth's core were formed in exploding stars and are being expended, never replenished. So in a way our geothermal heat is stored stellar energy being released radioactively. The entire concept of an energy "source" is flawed anyway, since total energy is always conserved. All the energy was already there at the big bang. There is only flow. Entropy always wins in the end.


Indeed. Energy isn’t “used” so much as “spread out”. Too spread out and it isn’t useful anymore.


> The centers of planets don't get hot simply by being the center of planets. Ehhhhh... fill up a compressed air bottle and get back to me


Compressing something creates heat, but if it is already compressed, maintaining high pressure is it not a source of heat.


But high heat from the compression *is* a source of heat. It's not like the heat vanishes after hitting static pressures... Accretion is considered to be one of the main sources of core heat.


I think what /u/jweezy2045 and a few others were trying to clarify is that "geothermal energy" isn't a specific fundamental form of energy such as gravitational energy or nuclear binding energy; it's a broad umbrella term incorporating all thermal energy flux through any particular geosystem (Earth's subsurface, a rogue planet's ocean or ice mantle etc). Many different processes contribute to what constitutes, at any given location, a source of "geothermal energy" - this could be radioactive decay, heat anomalies (hot-spots/subduction zones), regional variation in crustal thickness, and tidal forcing. The OP to which they replied seemed surprised at the fact that the heat in this rogue-planet-moon system was generated by tidal forcing and juxtaposed that with geothermal energy, as though the two are somehow distinct or different. They're not, considering that tidal forcing induces geothermal energy in a moon's (or planet's) medium. I think it's safe to say that people tried to explain that geothermal energy isn't a thing on its own the way, say, gravitational energy is, but that it refers to any thermal process in a planet's subsurface (which, ultimately, can be the result of any number of physical processes including tidal forcing).


Yes, this is what I was saying.


Tidal friction occurs primarily far from the center of mass, not at the core.


A large enough planet like the Earth generates much of its internal heat through radioactive decay.


I never realized gravitational pull generated enough friction to actually produce a significant amount of heat. Fascinating.


They can cause flares on white dwarfs where flares dont occur. There is a mechanism of tidal friction which results in the tidal heating occurring at the surface of the white dwarf (usually in stars tidal heating occurs deep inside the interior). The heating can be enough to spark local nuclear fusion and consequently a flare.


If you think about how much energy it must take to cause the tides, and that almost all of that comes from the moon, it starts to come into perspective. That's a LOT of mass being shifted around


How likely do we think a rogue planet is to retain its moon(s)? I'd have guessed the interactions that eject a planet from a solar system would perturb the moons of said planet in such a way that collision or ejection have a significant chance of happening. I'd also imagine the odds of a rogue planet capturing a new moon in interstellar space would be astronomically small.


One way is to simply have a long period orbiting giant planet and have the star evolve off the main sequence. The mass loss can cause the planet to migrate far enough to become unbound.


So Neptune in 4-5 billion years?


Makes sense that an ejected planet might lose moons in the process… but not necessarily all of them…


Agreed. Especially moons close enough to a large enough exoplanet to be tidally heated.


And if the ejection process distorts the moon's orbit to be more elliptical, so much the better.


Extremely likely actually. Mostly because no such great forces are required to eject rogue planets. Most rogue planets will have formed in unstable orbits, potential in binary star systems, and simply slip away during development. Others will actually have been on the road to development into stars, but have failed to do so, never being ejected from anything. Those which were ejected are unlikely to have been subjected to any forces large enough to destroy their moons, as such forces would be enough to destroy the planet. Think about it, any gravitational force large enough to eject a planet will come from a body with a roche limit much larger than the planet's. In order to steal the moons or send them crashing into the planet the approach would have to be perilously close to destroying the planet itself. The most common "true" ejection scenario is a fast moving star approaching a slower moving star at a distance lower than 100ish AU. Planets orbiting in the direction of the approach but behind it will be accelerated into much higher and eccentric orbits, potentially escape velocity, without ever approaching the other star closely enough to have significant forces acted upon them.


Does that mean our solar system might have made a rogue planet?


There is a model that explains the same as our planets are structured with a fivth gas giant that was ejected somewhere along the way. https://en.wikipedia.org/wiki/Five-planet_Nice_model


Yes, there's even some evidence of such. We think Jupiter migrated outwards, Uranus is on an angle like it had an encounter with a large body, something stole Venus' rotational energy billions of years before it should have, the clusters of comets and large TNOs have no current explanation. Any such planet or planets would have been ejected billions of years ago and be basically undetectable.


After trying to imagine life on a planet like this I almost want to apologize to any rogue ones out there that were ejected. You know before they attack us with a fleet of fusion rocket bombardment in revenge.


>I'd also imagine the odds of a rogue planet capturing a new moon in interstellar space would be astronomically small. In space, all odds are astronomical.


If it was stuck it could reform a moon.


Odds of a collision to reform a moon seem highly unlikely.


Tl;dr: moons around large exoplanets can have liquid water because of tidal heating.


They could have SeaWorld on them, doesn't really matter until we can reach them.


I mean, if we could prove they had a functioning Sea World location I feel like it would matter even if we couldnt get there.


Play zoo tycoon, then you can make one yourself :P


96% of the visible universe is forever unreachable, is it not worth studying?


Herein lies the difference between a scientist and an engineer.


This guy, talking about weather or not we can get there. When we should be asking why should we go there?


Sorry to be that guy but whether


You're right. I never knew how to spell it like that.


I'm glad I could be of service friend!








The classic sci-fi movie “When Worlds Collide” was based on a book of the same name by P. Wiley and E. Balmer. In the story, a rogue star or planet, depending on which media you’re talking about, is on a course to destroy the Earth. But the body has a companion that is Earth-sized and had oceans, an atmosphere… and cities!


Its also [a pretty cool song by Powerman 5000.](https://youtu.be/lsV500W4BHU) Fun fact the lead singer is Rob Zombie's brother.


If there's life in the ocean of a moon of a rogue planet, it's probably similar to Archaea that live in hydrothermal vents on the sea floor here on Earth, and utilizes chemosynthesis to live. Here's a NOAA video about life in a hydrothermal vent: https://oceantoday.noaa.gov/lifeonavent/welcome.html


Shhh! dont spoil the secret. we dont want every hipster / Influencer going there.


I had never heard of tidal heating before. This is amazing news! You know what this means it means that perhaps humanity stands a chance even after the sun runs out of fuel. I always assumed that that would be the end, that everything would just get colder and colder and we would be done for BUT if these moons are thermally heated by gravitational forces, that isn't dependent upon the sun and Jupiter gravitational field isn't going to lessen. Perhaps we could set up a colony that could survive there?


When the sun "runs out of fuel," it won't just fizzle and fade like a dying candle light. It will turn into a red giant and push its boundaries well past our orbit, consuming our planet in the process.


That is trespassing and not allowed according to zoning and city regulations


What about Jupiter? Would the boundaries of the expanding red giant reach Jupiter?


No, and earth might escape being consumed, but it would be scorched. Titan, and the other moons around Saturn and Jupiter will have earth like temperatures for a while, at least until the sun turns into a white dwarf.


I'd be somewhat surprised if humans survive for another 5+ billion years on earth without experiencing some type of mass extinction event. If technology hasn't evolved enough to develop interstellar travel in that same timeframe I would also be kinda surprised.


Over 5 billion years of human civilization at our *current* technological level, we'd *accidentally* colonize other star systems even if we weren't trying.


All you need is a tiny ship with plant spores and seeds to terraform a planet, if you're willing to wait a few thousand years. Then you can send a tiny ship with fertilized eggs and a bioreactor to grow humans and then have a simple robot take care of them for a few years until they can move and a computer to teach them language. We can literally build that right now with current technology for the first part. All you need is time.


Yeah, within 500 years (and probably substantially earlier), we're going to have sufficiently intelligent AI and robotics to build intelligent, humanoid robots. There's nothing impossible about it - we're essentially biological robots ourselves, and if we can be as smart as we are, our machines can as well, ultimately (and honestly, to raise humans they likely don't even need to be). It's just a matter of time until this is possible, if it isn't already.


Watch as our selfish interstellar spawn don't want to study language. Kids in the 2200s just aren't like they used to be!


Just be careful not to fall down any large holes


Too bad humans makes decision for their individual life span.


Not all the time. Every day countless humans make decisions solely for the benefit of future generations. The problem is that the right long-term decision is rarely the most immediately *profitable* decision.


Short term gain for long term pain.


We'll be traveling between stars long before a billion years is up.


Or dead. My money is on dead.


My money as well. Definitely talking hypothetical with this.


yeah. I'm betting 100 millennia before we are available to get to someplace outside our local star clusters. Before that I'd say we just need a way to stimulate a womb using machines and we can send people while they are still cells to places thousands of years away with extensive slowdown of human growth. Basically cellular hypothermia. AI robots take care of regular maintenance and eventually, teaching the kids. I image a few humans would be "awoken" 20 years before everyone else to act as human teachers for those uniquely human things kids ask. Even after thousands of years I bet the 1 thing we won't be able to completely solve will be the behavior, nature and complete workings of how and why the human mind functions and asks the questions it does. The brain is just too fking complex plus you can't just crack a man's head open to study more accurately unlike most other things.


Rather than launching babies in space , I say we should research more on Cryo sleep. This is a more promising way of interstellar travel.


Theres the small problem of, who would be willing to do that? Sure, you might find people that are willing to effectively "die" in the sense that, when they go cryo sleep everyone they ever knew will most likely be dead, because space is huge, and i doubt we'll ever go fast enough to solve that problem. The other suggestion would make (inhumane) sense in a way that you can easily manipulate/teach the cryobabies in a way that they wouldnt know about how we (currently) live as families and have friends, lovers etc. Hopefully im wrong on both, but in current state of things i dont think i am.


A maintenance system for a few or single cells is a lot more manageable than for trillions per individual. Sometimes, the simpler option just makes more sense.


When you reach relativistic speeds, a single human lifespan is enough time to get almost anywhere. It’s the return trip that screws it up. You can’t send information (or people) back to where you started from when traveling those distances because of the time/space traveled.


>You can’t send information (or people) back to where you started from Or rather, you can't send people back to *when* you started from. It's a plot point in Ender's Game and in Interstellar.


Space would have moved too. Space time. Not space and time. It’s part of the plot of every story that’s ever been told, since that’s how physics works. :)


I am so happy I live in a time where we can learn as much as we do about the universe. This stuff blows my mind.


Where does the energy in tidal heating actually come from though? Is it orbital decay? Because if not shouldnt that violate conservation of energy?


Yes. Same forces that cause ocean tides here on earth. The energy to move that water is from the angular momentum of the earth/moon system. Luckily, there is enough kinetic energy in that system to last billions of years.


Either orbital decay or stealing the rotational energy of the planet. The Moon is slowly stealing the Earth’s rotational energy, which is why it’s orbit is slowly moving higher, not decaying. Wait a minute! Actually, orbital decay doesn’t work at all to produce tidal heating…. Unless, perhaps, the moon’s orbit is initially eccentric… So, our own Moon probably does not experience any significant tidal heating. Bottom line… tidal heating takes its energy either from the rotation of the moon or possibly from decay of the eccentricity of the moon’s orbit.


The energy comes from orbital energy of the system. The tidal force causes stresses through the body which acts to transfer angular momentum between the two objects. While angular momentum is conserved, kinetic (spin and orbital) energy is not and some kinetic energy is converted to heat due to friction. You could then say that over a long enough timescale the heat from the tidal friction, where ever it is deposited, would find itself at the surface where it would be radiated into space.


But how thick would the atomosphere have to be to preserve enough heat in interstellar space? I assume it would need specific gases like CO2 and hydrogen? Also, what about the radiation? Around Jupiter, Io is the one most affected by tidal forces, but is also bombarded with an incredible amount of radiation, lethal for any life as we know it. I don't see how an exomoon could be close enough to the parent gas giant to be heated but safe from radiations at the same time. Am I missing something?


Most of Jupiter’s radiation comes from its magnetic field trapping protons emitted by the Sun. So, this would be much less an issue for a free-floating planet distant from any star. There would still be some trapping of cosmic rays, but this ought to be a far smaller effect. Also, not all giant planets have magnetic fields of equal strength. I think Saturn has a much weaker magnetic field than does Jupiter. Among other things, the strength would probably depend on the rotation rate of the planet.


Just wild to think of a civilization on a planet that is roaming through space unattached to a sun


does this mean that if a moon of jupiter had been more the size of earth, it could have held onto a thick atmosphere and a warmer climate?


To my understanding aren't rogue planets ones outside of any star's gravitational field making they fly through empty and cold space alone? even if gas giants radiate some heat and light wouldn't that be too little for any complex lifeform? Edit: read the article lmao Still weird as fuck but that's space for you 🤷‍♂️


Wouldn't a rogue planet be frozen over as well as any moons orbiting it?


Sure but... There's 90 other problems with rouge planets that water wouldn't be able to fix.


They could be habitable until we inhabit them.


How do we detect rouge planets? Or its moons? In my understanding we find planets by looking at the stars they are orbiting. Differences in brightness or position. Obviously, this wouldn't work here.


How could they have liquid water if they are a rogue planet?


What a useless article. No substance at all to it.


How would that work out then because the rogue planet has no parent Star and I know how orbits work


There would be no "sun" it orbits. Heat is generally from tidal forces and light would be scarce.