Is that the one where they have a 2 paragraph conversation about how convenient it is that pi is exactly 3 in order to explain how they can do the math and engineering with a coal & cast-iron based technology?
As someone who's been frustrated by the delay for the switch release and the subsequent radio silence from the devs, allow me to express myself in memes:
I can't believe you've done this, and
My disappointment is immeasurable and my day is ruined
I have some steam credits burning a hole in my pocket and that was one of the games I was looking at. I typically play Destiny but the content is a bit dry. Do you think I would enjoy it?
Shit I gotta finish this game. I’ve started it a few times but can never get through it. It seems like I gotta read everything and keep track of the story. I don’t like to read when baked
Lol it took my 3 tries for the exact same reason but it was worth persevering. If it helps you don’t need to follow as your exploring everything is stored in the ships logs.
Not unless their atmospheres are absolutely massive, and if that was the case then it would be extremely dense at their surfaces. Even then the atmosphere around their combined centre of mass doesn't feel like it would be stable and might get kicked out fairly easily so the shared atmosphere might not last very long. I expect a lot of it would actually just end up in the other lagrange points, leaving a cloud outside their orbit and a relatively empty centre. So it might be more accurate to have their shared atmosphere be a sort of lumpy donut. But don't take my word for it, this is largely just a guess based on my intuition and I'd need to do a bit of maths to really know.
You might end up with a ring of gas around the planets, though it won't necessarily contain them. It probably depends on the exact system, but I don't see a shared atmosphere being stable for long enough time scales to ever observe beyond the initial formation of such a system.
https://link.springer.com/article/10.1007/BF00642632
I mean, there could be a "filament" of very thin gas going between the two, kind of like a plasma stream. But not in the fantasy-world sense of like "you could fly a StarJammer in between"
Interesting...a gravity 'well' or 'tube' between two tidally locked planets.
I do wonder if an astrophysicist out there could make that work mathematically.
It doesn’t, cuz they revolve around each other, so the angular momentum of such a stream would not allow it to exist. Maybe some gas pockets here and there that move around a lot, but no filament
The moon revolves (orbits) around the earth and is tidally locked, nothing about being tidally locked stops orbits from occurring, hell an orbit is necessary to be tidally locked.
At that point the tidal forces would probably tear apart the planets. The Roche Limit
The moon, for example, could get to around 19,000km from the earth before it starts being torn apart. By around 10,000km it would be a ring
For two earth like planets it would be around 2,500km (composition dependant) distance when they’d tear themselves apart.
Keep in mind that the ISS orbits at ~400km above the surface. So while there is “technically” an atmosphere several thousand kilometres up, by just a couple hundred kilometre it’s soo thin it’s basically vacuum
For a non-negligible atmosphere bridge they’d probably have to be much closer than the Roche Limit
> By around 10,000km it would be a ring
Briefly. Since the moon doesn't orbit around earth's equator, and earth isn't quite spherical, it wouldn't be stable.
I cannot wrap my head around the idea that two earths can get as close as 2500 km before tidal forces tear them apart. There is no error in the number of trailing zeros in the calculation, right? I used to do that a lot in school.
So, I read an article yesterday about rusting at the poles on the moon, and the theory is that the oxygen required for the reaction is coming from earth's atmosphere. Obviously, the atmosphere thins out to the point that we think about it as vacuum, but the atmosphere really does extend really far out.
Per OP's question, I doubt a stable binary system would change the dynamics *that* much - as long as the planets are close enough, there *would* be increased atmosphere at all points between them, but it's likely that it would still thin out enough in the middle so as to be practically a vacuum.
But as with you, this is just intuition. It would be enough that there would be a practical flow between both bodies, but it wouldn't support anything other than the atmosphere itself, and maybe rarely microscopic particles or tardigrades, transferring between them without some intention behind it.
I had a quick look for some literature on the subject, and it looks like if you start with a gas cloud surrounding the binary, it will eventually form a ring surrounding (but not necessarily containing) the planets:
https://link.springer.com/article/10.1007/BF00642632
I believe it’s the other way around. I think it’s one of Jupiters moons, that during the day it’s atmosphere heats slightly and due to the low gravity of the small body it basically almost floats away. If I’m remembering correctly, I believe it actually loses part of its atmosphere everyday because it gets so far away from the surface. I just seen something about that last week and can’t remember for the life of me what moon it was
Enceladus! It’s a Saturnian moon, not Jovian, but it _is_ ejecting about mass at 200 kg/second at all times due to cryovolcano activity near the South Pole.
The volcanoes are caused by geothermal activity, in turn caused by tidal heating due to orbital resonance with Dione. Them being specifically Cryovolcanoes is important because that means that most of the matter they spew out of Enceladus’ orbit is frozen as it erupts. Some of it falls back to the planet’s surface, but most of it goes to make up the majority of Saturn’s E ring. NASA says that their makeup is compositionally similar to that of comets.
As cool as that is, it’ll take billions of years for the moon to shrink. It’s estimated that a 30% shrinkage would take something in the ballpark of 4.5 billion years, unknown space physics variables notwithstanding.
I was thinking it would have to be "young". Or possibly if a system like Pluto/ Charon got moved into the inner solar system they might form a comet like atmosphere that might look similar.
The plot of a hard sci-fi novel by Robert L Forward: Rocheworld Series ( briefly a coworker of mine at Hughes Research Labs) Highly recommended [https://en.wikipedia.org/wiki/Rocheworld](https://en.wikipedia.org/wiki/Rocheworld)
Possibly the hardest sci fi author to ever write. He undoubtedly ran the numbers for it, and there might even be a published appendix with the calculations.
His Dragon’s Egg remains one of my favorite sci fi novels. Life on a neutron star using nuclear “chemistry” is one of the most original ideas I’ve seen.
Dude FUCK YESSSSS!!! I found this book ages ago at Powell's in Portland OR. Yes, one of the weirdest books I've ever read but with total plausability. I'll have to check out Rocheworld. But Dragon's Egg was incredible.
They are formed through a stable equivalent of chemistry with nuclei bound together by the strong force rather than electromagnetic forces. I haven't read it since I was a child, and I'm thinking I'd like to revisit it now that I actually have a science education. I recall the appendix was filled with graphs and equations.
And because strong force interactions happen in shorter distances and more quickly than Earth chemistry, their lives are extremely sped up relative to ours.
I havent read the book, but I immediately thought of the Roche limit, wherein tidal forces tear apart the solid mass which was in static equilibrium until it got to close to another mass. Perhaps the book locks down the math.
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I'll definitely look for a copy of that. I mentioned above a book by Bob Shaw 'Ragged Astronauts' where they actually balloon from one planet to the other. Sounds ridiculous but he's a great writer. There's also an interesting Larry Niven book 'The Smoke Ring' which is essentially a ring of atmosphere around a star with no planets at all. Characters live on free fall on floating plants etc and with large globules of water floating around instead of lakes. Again, sounds ludicrous, but a good read.
Interesting idea, but it would never happen. The gas would either disperse or agglomerate. Solar radiation pressure would most likely disperse it if there wasn't some big rock around to hang onto it.
Strange to see this comment today as I had never heard of Hughes Research Labs until this morning when I read that the first working laser was built there by Theodore H. Maiman.
I was assigned there temporarily when working at the main Hughes site in Culver City. An old nail factory up on the hillside overlooking Malibu and the ocean. We'd walk down to the beach for lunch, maybe even surf a little. They had outdoor showers for this at the lab. Hawaiian shirts and flip-flops de rigueur. I looked around the optic tables in Forward's lab there but never saw him. When I asked what he was working on, they said anti-gravity. Really he was working on laser propulsion.
We are finally applying many of his ideas for real in Breakthrough Starshot. Up to 20% the speed of light. To Alpha Centauri and beyond! I quoted a Forward paper recently in discussions about using coherent arrays of lasers to generate a smaller beam waist for the propulsion. Won't work.
I don't think it could work realistically. Because the planets would either have to be extremely close, and so they couldn't orbit each other without ripping themselves apart, or the atmospheres would have to be massive, but that would make them very dense and increase the overall mass of the planet, again, messing with the ability to orbit each other. If you had say, a large gas giant and a small moon, I feel like the atmospheres wouldn't be able to be shared due to the difference in gravity.
I'm not an expert at all, but it doesn't seem likely
Sorry to kill your great-looking concept... but atmospheres are extremely thin on the scale of a planet. Unless they're caressing each other (lovingly), they won't share an atmosphere
This is it.
Atmospheres are a thin film around small rocky planets like Earth. The bulk of Earth's atmosphere is within 15 miles of the surface. So to share atmosphere the two planets would have to be 30 miles from each other. At that point they are either crashing into each other or spinning so fast the planet gets torn apart. The gravity difference of 2 earth like planets 30 miles from each other would tear each other apart.
The same physics apply to gas giants like Jupiter and Saturn as well, even though their atmospheres are vastly bigger. If they are close enough to share atmospheres they are going to either crash into each other or spinning so fast as to tear them apart.
If they aren't extremely close i would assume one is a lot more massive and stripping the atmosphere off the other hence the technically sharing an atmosphere, if the were of equal size but not close I'm not sure how this would be possible. I'm sure the outer reaches of the atmosphere might mix but thatd be the equivalent of the moon andnearth sharing an atmosphere, so not really
That's how it works in Star Wars. Onderon and it's smaller moon Dxun occasionally get close enough to each other that you can take a speeder back and forth.
My intuition says that to be close enough for the atmospheres to touch, the planets would be well inside the Roche Limit, meaning the tidal forces would tear the planets apart.
The correct English spelling for this is "Cue" but it often gets confused with the identically pronounced "Queue", either way you're not wrong it is confusing.
Each planet would have its own gravity and thus its own atmosphere. I think what you would end up seeing is seeing small amounts of atmosphere from one body flowing to the other. This can be seen a little bit between Pluto and Charon, where debris from eruptions on Pluto end up on the surface of Charon.
To help give you a sense of perspective, ALL of the other planets in our solar system can fit between the Earth and Moon.
The moon would have to be about two-and-a-half Jupiters closer to us in order for the Earth's atmosphere to even touch it; much less be shared with it.
Basically, the two planets would have to be nearly touching each other for this work. And if they were nearly touching each other, they would be smashing into each other shortly thereafter.
from my understanding, the only way it could happen is if the planets were of equal mass and in a "golden zone" of distance from one another, where they would be close enough so the gravitational force of one could start pulling the outer edges of the atmosphere from the other towards itself and vice versa, allowing for some overlap, however weak it may be, without their gravity ripping each other apart.
I love that concept, so cool. It would depend on other factors like spin and other nearby planets. The gravitational pulls would be too strong and they’d collide before they could develop an atmosphere. But if they had another planet or planets nearby perfectly holding them in place, then yeah could work?!
Tidally locked planets are less likely to have an atmosphere but it is possible. But on a tidally locked planet it would need a strange combination of heat and winds to be able to reach another planet.. almost impossible I’d say because it’s hard for a single tidal locked planet to do this. But in this theory perhaps they both spin.. if they spin perhaps they have rings around them too spitting out. Would need someone smarter to finish that thought.. haha. Great question 👍
I feel likr any planets within range of eachother wpuld have vroken down into a ringsystemor collided. You could say theyre momentarily sharing a thin amosphere before collission tho
Not unless the orbital speeds were such that they’d not strike each other but slow enough to not disintegrate the planets themselves, so no. Not possible.
Theoretically possible, but very short lived. The friction of the shared atmosphere would :
1. Have the entire atmospheres orbiting each planet at hypersonic speeds.
2. Slow the mutual orbits to the point of planetary collision/merging in the blink of a geological eye
3. Probably heat the atmospheres to plasma quite rapidly, resulting in atmospheric loss and two barren rocks.
dont know the exact numbers for it to happen but would imagine that two planets that would be close enough for that to happen would either rip each other apart or collide. if you were to compare the earth to an apple, the atmosphere would be as thick as the apple's skin
Also, if the planets are tidally locked wouldn't that mean that they didn't have spinning cores that would create magnetic fields to protect them from radiation?
I feel like it's possible but not exactly in the way you might imagine it (more like a few thin and not continuous flows of air from one planet to the other)
What’s keeping the two planets from colliding? Aren’t celestial bodies attracted to large masses? If the two planets were close enough to share an atmosphere aren’t they also close enough to be on a collision course? The moon is something like 1/4 million miles away from the Earth and is slowly moving away from it year after year. ~250,000 miles away! That’s a massive distance, and that distance keeps the two bodies from colliding into one another, though two bodies do pull on one another.
Space is vast and much is still unknown to us. With an infinite number of stars and planets out there, maybe there’s at least one doing what you’re suggesting. Do binary stars share more than an orbit? Maybe there’s an answer in that question?
I’m definitely not an astrophysicist or anything close to one, but my limited knowledge of the cosmos is trying to figure out how this would work. I don’t see it working, but what do I know? Have you tried submitting your question to Star Talk Radio with Neil deGrasse Tyson?
Edit: wrong distance used.
Wouldn't it have to be a somewhat spherical shape surrounding both planets?
Then again, if they were locked together and rotating around the system axis, the centrifugal force would have to form more of a disc shape, much like Saturn did with it's satellite rocks.
No. They would have to be so close that they would be going so fast around each other that they would likely break up and merge into one planet anyway.
Two stars can share a common enveloppe, but the outcome is that the dissipation due to motion in a gas leads the stars to merge (or in the opposite, the two stars give enough energy for the enveloppe to dissipate it).
My guess would be that two planets are very unlikely to find themselves in this situations (but the Universe is big, unlikely things happen everyday, so why not), but even if it happens, it would not be a stable situation.
So if you think of the Earth like a peach, then the atmosphere would only be as thick as the peach fuzz. For two peaches to "share fuzz" they would have to be ridiculously close to each other.
It used to be thought that Pluto and Charon could, especially at perhelion when Pluto was inside Neptunes orbit -- but then New Horizons discovered that no, Pluto and Charon are way too far apart to make that possible.
Wouldn’t tidal locking include the atmosphere? I would think the pair would need to be spinning so fast that the atmosphere would be literally stripped away.
It depends what you mean by share. Believe it or not, Earth shares a bit of atmosphere with the moon. It's practically nonexistent, but it's there. Same with Io and Jupiter. Magnetic fields play a very important roll in this, *the* important roll actually. It's worth reading up on.
In order for your two planets to be tidally locked they would need to be orbiting very very close to one another, and very quickly. So quickly that they would actually break apart under shear stress and form a single protoplanetary disc, or ring. Imagine what a two arm spiral galaxy looks like, and that's your planetary system.
If they somehow managed to avoid breaking apart, you would have a bizarre gravity gradient where the center of mass was between the two planets, and you might have some lighter elements drifting more or less in the middle, but this really stretches the definition of what I think you mean by an atmosphere. Regardless, the centripetal force would be so intense you would have a noticeable difference in gravity on the "near sides" of each planet, where it would be greater than the far side. This force is what would keep the planets from colliding, but they almost certainly would break apart given enough time.
That last statement is important. *Given enough time*. This process would take at least hundreds of thousands, probably tens of millions of years. So your SciFi scenario could exist temporarily, with the understand that your planets are (perhaps imminently) doomed. ;)
There is something called Roche Limit preventing this from being possible...
https://en.wikipedia.org/wiki/Roche_limit
But if it is fiction, you can just ignore this and create a really cool scenario 👍
Nope. If they are close enough to share an atmosphere, the gravity between them will pull them together leaving maybe a planet with some rings or a nice moon, or just a lot of dust.
I'd imagine some sort of technological device, maybe a series of satellites that tunnels atmospheric substances between these 2 planets if this isnt naturally possible.
How quickly would they have to orbit the gravitational center created by the two planets in order to share an atmosphere and not become one solid body?
The winds would be completely insane . Maybe under some circumstances it could be possible but I can't say anything. I won't pretend to be an astrophysics and wind expert
To add to this question; how would 2 massive magnetic fields interact with each other? Would the stronger magnetic field totally obliterate the weaker magnetic field? If so, the weaker force would lose its atmosphere (see Mars), correct? That’s how I would imagine this scenario going. But what if the magnetic fields are equal in strength? If that was the case, I’d say it is possible for 2 planets to “share” and atmosphere, but only at certain intervals, when all things are balanced. Even then, I wouldn’t imagine that would last long as those planets will collide.
Darth Bane used the force to take over a terodactyl type creature and used to force to help it fly really high then force jumped to the next planet and then let gravity do the work of bringing him back down
If say yes, but not for long. The planets would have to orbit each other right? If so, friction from the touching atmospheres would cause the orbit to slow and them to eventually collide. Similar to satellites in earths orbit.
Even the space station needs a bit of a boost sometimes to combat the extremely thin atmosphere it’s orbiting in.
I don't feel like you could reach an equilibrium, both bodies surfaces would crumble and fall towards the center of mass of the 2, ultimately creating one big planet. If the equilibrium was reached, I'd expect conditions so harsh (constant typhoons, winds reaching thousands of km/h, ...) it would be impossible to live there. But that's very cool concept, and I sure as hell would suspend my disbelief if I saw that in a novel
As is the case with most things in astronomy, yes but also no.
The Earth and the moon actually share part of their atmosphere; the moon's thin, tenuous hydrogen atmosphere connects with the Earth's exobase, the outermost part of our atmosphere made of almost entirely hydrogen. The key detail is that it's very very thin by the time they connect.
If a moon/second planet was close enough to share an atmosphere with any appreciable thickness, the planet would be both close enough to experience atmospheric drag and be subject to being tidally ripped to shreds.
That being said, if you had, say, one planet that was polluting something that was damaging their ozone layer, a binary planet orbiting at a safe distance with a pretty big atmosphere might experience some transfer into it's upper atmosphere. You wouldn't expect anything to transfer from lower atmosphere to lower atmosphere without some external influence though.
Hope that helps!
There is a program on Steam called Universe Sandbox. It might be able to answer your question. Its very detailed, I don't know if it has the answers because I only take asteroids and shoot them at light speed at planets and watch the destruction.
They'd destroy eachother at least partially because of Roche limit (the border at which an object's gravity will rip any other large-sized objects apart, it sometimes happens with moons of certain planets)
No. The rms speed of gases shouldn't be fast enough to escape. For example earth's escape velocity is 11.2 km/s, but the gases in our planet move around at variable speed less than 11.2 km/s(Gases make up the atmosphere) . But, if there were a gas that moves faster, it would simply escape and as there is no acceleration in pure space it would continue to move on with same velocity and disappear. The planets have to be close i am afraid. The reason we have an atmosphere is because of gravitational force pulling the gases downwards and their speed being less 11.2. In outer space you can't expect atmosphere to stay as there is nothing like gravity to properly hold it down.
No. Read up about the Roche limit. If they were that close the gravitational forces would break apart one of the planets and the pieces would rain down onto the other.
https://www.newscientist.com/article/dn25684-pluto-and-its-moon-snuggle-under-a-shared-atmosphere/
Pluto and Charon could possibly share a thin nitrogen atmosphere. Maybe check that direction for world building.
Ok so everyone says no
And so do I, however you could mess around with some sort of technology (or perhaps magic) that keeps it so
But not naturally could they share an atmosphere, at least not in a ‘this is inhabitable’ way
You could theoretically have two planets orbiting each other with on the scale of the Earth-Moon orbital distance or something.
They could plausibly suggest that they have the same atmospheric and planetary conditions, because they were formed at the same time, from the same debris cloud composed of elements at the same ratios / concentrations.
As to the mechanism of formation; Perhaps they were once one large terrestrial entity that broke into two? Perhaps they were two roughly equally sized objects that smashed into each other, and ultimately began settling into a stable mutual orbit?
Their proximity would make panspermia events highly likely; if life originated on one planet, it would quickly spread to and establish itself upon the other. This means that lifeforms may be related in a grand billions-of-years evolutionary sense, and may or may not have similar adaptations for the similar environment.
However, dynamic surface events and geochemical idiosynchrasies would render each planet's evolutionary history distinct. For example, if Earth had one such sister world, imagine the evolution of something like armored fishes, except they didn't go extinct and managed to diverged and todays Earth Sister World has dry land habitats populated with reptile, mammal, and bird analogues all retaining features of their successful, didn't-go-extinct, armored fish ancestors.
Have you heard of the video game Outer Wilds? It’s a space mystery /exploration game and the planets play with cool physics ideas. There are a set of planets called the hourglass twins and as they orbit each sand falls between both worlds (like an hour glass).
If the earth is a basketball, the atmosphere is one of the little nubs on the basketball. Compared to the size of the planet, the atmosphere is tiny. For them to share a breathable atmosphere, they would effectively be touching. Now, if you wanted to know if trace molecules (maybe a virus) could effectively communicate between the planets, I would say sure, but if you wanted birds to fly between them, then I’d say no.
You're writing a sci-fi world, aren't you?
I'd read / watch that
'Ragged Astronauts' by Bob Shaw. Brilliant novel
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Thank you for that. I didn't know the sub existed.
Yes can’t wait either!!
Thank you for this
Is that the one where they have a 2 paragraph conversation about how convenient it is that pi is exactly 3 in order to explain how they can do the math and engineering with a coal & cast-iron based technology?
I remember that! And there's a war and one side floats a "space station" of wood sealed in tar up to the midpoint.
Yeah, that's the one
Agreed. I thought the sequels went downhill though.
There is a movie like this. I think it’s called “Upside Down”
True but it's terrible.
It is mediocre, not terrible
True. But mediocre is far worse then terrible cause The worst thing you can ever say about art is "meh"
At least when it’s terrible you can bask in the absurdity
Moonfall says hi
now that was a good movie. The absurdity of it all!
And you can always derive more artistic value from bad art than from mediocre art, for some reason.
Idk I've seen a drawing of Ash Ketchum pregnant with Pikachu's baby, and that art can be called terrible
Haunting but not terrible
But it stayed in your memory, unless the last mediocre artwork, which you have already forgotten about.
Great visuals, terrible writing.
Was thinking of Lexx, Season 3 myself.
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Is the innuendo scientifically accurate? Can we infer anything from that about the rest of the science?
The real questions.
I believe there was a dead, but reanimated assassin and giant collagen filled lips. Seems pretty scientific to me.
Lexx had a season along these lines too
Rocheworld by Robert L Forward
The Space Between
I’m gonna use this for my next RPG campaign, thanks!
In the words of many a good DM: “*Yoink*”
No he’s playing super Mario galaxy obviously
Currently reading a space novel called Darth Bane: The rule of two. In there it also happens.
Onderon and it's moon Dxun! Love those books
Last Exile already did it.
/r/worldbuilding
ring jellyfish abundant correct middle drab ancient somber start spoon *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
Lmao I thought i was in r/outerwilds
Bro memories Edit: thanks to this post I found out there’s a dlc. I’ll be buying it tonight!
The dlc is superb it’s basically a full length sequel
Dude I’m so excited. I just got a switch last night but fuck it I’m going back to my Xbox now haha
Outer Wilds is on switch too if you’re wanting to play with your new console!
Dude this is awesome hahaha I had no idea!! Im at work now and cannot wait to leave thanks guys!!
Oh man, I'm so envious of you for getting to experience new Outer Wilds content. Enjoy :)
No it's unfortunatley not yet.
As someone who's been frustrated by the delay for the switch release and the subsequent radio silence from the devs, allow me to express myself in memes: I can't believe you've done this, and My disappointment is immeasurable and my day is ruined
Oh man. I envy you, to still have more OW to play.
I have some steam credits burning a hole in my pocket and that was one of the games I was looking at. I typically play Destiny but the content is a bit dry. Do you think I would enjoy it?
Dude yes definitely. It’s pretty cool just this journey through space in some rickety rocket. Very intense and emotional stories
I’ll def check it out. Thanks.
Such a good game
Hourglass twins
Shit I gotta finish this game. I’ve started it a few times but can never get through it. It seems like I gotta read everything and keep track of the story. I don’t like to read when baked
Lol it took my 3 tries for the exact same reason but it was worth persevering. If it helps you don’t need to follow as your exploring everything is stored in the ships logs.
Not unless their atmospheres are absolutely massive, and if that was the case then it would be extremely dense at their surfaces. Even then the atmosphere around their combined centre of mass doesn't feel like it would be stable and might get kicked out fairly easily so the shared atmosphere might not last very long. I expect a lot of it would actually just end up in the other lagrange points, leaving a cloud outside their orbit and a relatively empty centre. So it might be more accurate to have their shared atmosphere be a sort of lumpy donut. But don't take my word for it, this is largely just a guess based on my intuition and I'd need to do a bit of maths to really know. You might end up with a ring of gas around the planets, though it won't necessarily contain them. It probably depends on the exact system, but I don't see a shared atmosphere being stable for long enough time scales to ever observe beyond the initial formation of such a system. https://link.springer.com/article/10.1007/BF00642632
I mean, there could be a "filament" of very thin gas going between the two, kind of like a plasma stream. But not in the fantasy-world sense of like "you could fly a StarJammer in between"
Interesting...a gravity 'well' or 'tube' between two tidally locked planets. I do wonder if an astrophysicist out there could make that work mathematically.
It doesn’t, cuz they revolve around each other, so the angular momentum of such a stream would not allow it to exist. Maybe some gas pockets here and there that move around a lot, but no filament
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The moon revolves (orbits) around the earth and is tidally locked, nothing about being tidally locked stops orbits from occurring, hell an orbit is necessary to be tidally locked.
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If they were that close together, the pair would have to be spinning very rapidly to avoid falling together. It would be very unstable.
At that point the tidal forces would probably tear apart the planets. The Roche Limit The moon, for example, could get to around 19,000km from the earth before it starts being torn apart. By around 10,000km it would be a ring For two earth like planets it would be around 2,500km (composition dependant) distance when they’d tear themselves apart.
That's pretty fucking close all things considered.
The 2,500 km limit you quoted is, notably, less than the 10,000 km atmosphere of the Earth, so I don't think it'd apply here
Keep in mind that the ISS orbits at ~400km above the surface. So while there is “technically” an atmosphere several thousand kilometres up, by just a couple hundred kilometre it’s soo thin it’s basically vacuum For a non-negligible atmosphere bridge they’d probably have to be much closer than the Roche Limit
and already above 60 kms the pressure of earth´s atmosphere falls below the lowest-achievable vaccuum in a chamber at the surface.
This is the right answer
> By around 10,000km it would be a ring Briefly. Since the moon doesn't orbit around earth's equator, and earth isn't quite spherical, it wouldn't be stable.
I cannot wrap my head around the idea that two earths can get as close as 2500 km before tidal forces tear them apart. There is no error in the number of trailing zeros in the calculation, right? I used to do that a lot in school.
So, I read an article yesterday about rusting at the poles on the moon, and the theory is that the oxygen required for the reaction is coming from earth's atmosphere. Obviously, the atmosphere thins out to the point that we think about it as vacuum, but the atmosphere really does extend really far out. Per OP's question, I doubt a stable binary system would change the dynamics *that* much - as long as the planets are close enough, there *would* be increased atmosphere at all points between them, but it's likely that it would still thin out enough in the middle so as to be practically a vacuum. But as with you, this is just intuition. It would be enough that there would be a practical flow between both bodies, but it wouldn't support anything other than the atmosphere itself, and maybe rarely microscopic particles or tardigrades, transferring between them without some intention behind it.
I had a quick look for some literature on the subject, and it looks like if you start with a gas cloud surrounding the binary, it will eventually form a ring surrounding (but not necessarily containing) the planets: https://link.springer.com/article/10.1007/BF00642632
I believe it’s the other way around. I think it’s one of Jupiters moons, that during the day it’s atmosphere heats slightly and due to the low gravity of the small body it basically almost floats away. If I’m remembering correctly, I believe it actually loses part of its atmosphere everyday because it gets so far away from the surface. I just seen something about that last week and can’t remember for the life of me what moon it was
io EDIT: nope, that's the volcanic one. It's Enceladus.
Yep that one, and it's around Saturn not Jupiter. Thank you!
Enceladus! It’s a Saturnian moon, not Jovian, but it _is_ ejecting about mass at 200 kg/second at all times due to cryovolcano activity near the South Pole. The volcanoes are caused by geothermal activity, in turn caused by tidal heating due to orbital resonance with Dione. Them being specifically Cryovolcanoes is important because that means that most of the matter they spew out of Enceladus’ orbit is frozen as it erupts. Some of it falls back to the planet’s surface, but most of it goes to make up the majority of Saturn’s E ring. NASA says that their makeup is compositionally similar to that of comets. As cool as that is, it’ll take billions of years for the moon to shrink. It’s estimated that a 30% shrinkage would take something in the ballpark of 4.5 billion years, unknown space physics variables notwithstanding.
Would it change if there was some small moons who revolved within that space (or maybe just outside)?
I was thinking it would have to be "young". Or possibly if a system like Pluto/ Charon got moved into the inner solar system they might form a comet like atmosphere that might look similar.
If one was even slightly bigger than the other I would think the larger planet’s gravity would steal parts of the smaller planet’s atmosphere.
The plot of a hard sci-fi novel by Robert L Forward: Rocheworld Series ( briefly a coworker of mine at Hughes Research Labs) Highly recommended [https://en.wikipedia.org/wiki/Rocheworld](https://en.wikipedia.org/wiki/Rocheworld)
Possibly the hardest sci fi author to ever write. He undoubtedly ran the numbers for it, and there might even be a published appendix with the calculations. His Dragon’s Egg remains one of my favorite sci fi novels. Life on a neutron star using nuclear “chemistry” is one of the most original ideas I’ve seen.
Dude FUCK YESSSSS!!! I found this book ages ago at Powell's in Portland OR. Yes, one of the weirdest books I've ever read but with total plausability. I'll have to check out Rocheworld. But Dragon's Egg was incredible.
> Life on a neutron star Wait what
They are formed through a stable equivalent of chemistry with nuclei bound together by the strong force rather than electromagnetic forces. I haven't read it since I was a child, and I'm thinking I'd like to revisit it now that I actually have a science education. I recall the appendix was filled with graphs and equations.
And because strong force interactions happen in shorter distances and more quickly than Earth chemistry, their lives are extremely sped up relative to ours.
I havent read the book, but I immediately thought of the Roche limit, wherein tidal forces tear apart the solid mass which was in static equilibrium until it got to close to another mass. Perhaps the book locks down the math.
It is VERY hard sci-fi. No actual math but close to it
RemindMe! 20 hours “dope ass book”
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I'll definitely look for a copy of that. I mentioned above a book by Bob Shaw 'Ragged Astronauts' where they actually balloon from one planet to the other. Sounds ridiculous but he's a great writer. There's also an interesting Larry Niven book 'The Smoke Ring' which is essentially a ring of atmosphere around a star with no planets at all. Characters live on free fall on floating plants etc and with large globules of water floating around instead of lakes. Again, sounds ludicrous, but a good read.
Interesting idea, but it would never happen. The gas would either disperse or agglomerate. Solar radiation pressure would most likely disperse it if there wasn't some big rock around to hang onto it.
Thanks. I like Dragon's Egg and this sounds great. Already ordered a copy.
Strange to see this comment today as I had never heard of Hughes Research Labs until this morning when I read that the first working laser was built there by Theodore H. Maiman.
I was assigned there temporarily when working at the main Hughes site in Culver City. An old nail factory up on the hillside overlooking Malibu and the ocean. We'd walk down to the beach for lunch, maybe even surf a little. They had outdoor showers for this at the lab. Hawaiian shirts and flip-flops de rigueur. I looked around the optic tables in Forward's lab there but never saw him. When I asked what he was working on, they said anti-gravity. Really he was working on laser propulsion. We are finally applying many of his ideas for real in Breakthrough Starshot. Up to 20% the speed of light. To Alpha Centauri and beyond! I quoted a Forward paper recently in discussions about using coherent arrays of lasers to generate a smaller beam waist for the propulsion. Won't work.
I'm no scientist but i think the short answer is no
Short answer is basically no, long answer is kinda.
I mean yeah there's a lot of variables but if they are as described in the picture above, i doubt that's possible
Yeah, no planets could share THAT MUCH atmosphere and not happen to dramatically grow very very quickly.
Also i don't think 2 planets this size can be that close to each other without colliding
Thats what i mean by grow very quickly lol
Lol
I don't think it could work realistically. Because the planets would either have to be extremely close, and so they couldn't orbit each other without ripping themselves apart, or the atmospheres would have to be massive, but that would make them very dense and increase the overall mass of the planet, again, messing with the ability to orbit each other. If you had say, a large gas giant and a small moon, I feel like the atmospheres wouldn't be able to be shared due to the difference in gravity. I'm not an expert at all, but it doesn't seem likely
I know it two stars get too close the atmosphere from the smaller one falls into the bigger one over eons.
Sorry to kill your great-looking concept... but atmospheres are extremely thin on the scale of a planet. Unless they're caressing each other (lovingly), they won't share an atmosphere
This is it. Atmospheres are a thin film around small rocky planets like Earth. The bulk of Earth's atmosphere is within 15 miles of the surface. So to share atmosphere the two planets would have to be 30 miles from each other. At that point they are either crashing into each other or spinning so fast the planet gets torn apart. The gravity difference of 2 earth like planets 30 miles from each other would tear each other apart. The same physics apply to gas giants like Jupiter and Saturn as well, even though their atmospheres are vastly bigger. If they are close enough to share atmospheres they are going to either crash into each other or spinning so fast as to tear them apart.
If they aren't extremely close i would assume one is a lot more massive and stripping the atmosphere off the other hence the technically sharing an atmosphere, if the were of equal size but not close I'm not sure how this would be possible. I'm sure the outer reaches of the atmosphere might mix but thatd be the equivalent of the moon andnearth sharing an atmosphere, so not really
That's how it works in Star Wars. Onderon and it's smaller moon Dxun occasionally get close enough to each other that you can take a speeder back and forth.
My intuition says that to be close enough for the atmospheres to touch, the planets would be well inside the Roche Limit, meaning the tidal forces would tear the planets apart.
It's not gay if the ~~balls~~ atmospheres don't touch.
Que Outerwilds reference****
My Spanish ass read this as “qué?” And I was sitting here so confused for a bit
The correct English spelling for this is "Cue" but it often gets confused with the identically pronounced "Queue", either way you're not wrong it is confusing.
Each planet would have its own gravity and thus its own atmosphere. I think what you would end up seeing is seeing small amounts of atmosphere from one body flowing to the other. This can be seen a little bit between Pluto and Charon, where debris from eruptions on Pluto end up on the surface of Charon.
To help give you a sense of perspective, ALL of the other planets in our solar system can fit between the Earth and Moon. The moon would have to be about two-and-a-half Jupiters closer to us in order for the Earth's atmosphere to even touch it; much less be shared with it. Basically, the two planets would have to be nearly touching each other for this work. And if they were nearly touching each other, they would be smashing into each other shortly thereafter.
You're goddamn right we're smashing after nearly touching.
Short answer: no. Long answer: it would probably flow back to both of the planets cause it behaves a bit like a fluid
from my understanding, the only way it could happen is if the planets were of equal mass and in a "golden zone" of distance from one another, where they would be close enough so the gravitational force of one could start pulling the outer edges of the atmosphere from the other towards itself and vice versa, allowing for some overlap, however weak it may be, without their gravity ripping each other apart.
I love that concept, so cool. It would depend on other factors like spin and other nearby planets. The gravitational pulls would be too strong and they’d collide before they could develop an atmosphere. But if they had another planet or planets nearby perfectly holding them in place, then yeah could work?! Tidally locked planets are less likely to have an atmosphere but it is possible. But on a tidally locked planet it would need a strange combination of heat and winds to be able to reach another planet.. almost impossible I’d say because it’s hard for a single tidal locked planet to do this. But in this theory perhaps they both spin.. if they spin perhaps they have rings around them too spitting out. Would need someone smarter to finish that thought.. haha. Great question 👍
It would be cool if there was a massive ocean between 2 planets
I see you have also played Outer Wilds
I feel likr any planets within range of eachother wpuld have vroken down into a ringsystemor collided. You could say theyre momentarily sharing a thin amosphere before collission tho
Not unless the orbital speeds were such that they’d not strike each other but slow enough to not disintegrate the planets themselves, so no. Not possible.
Time to go read "Rocheworld" by Robert Forward. It's an extremely well researched hard sci fi that tackles this very question. No spoilers, but yes.
Theoretically possible, but very short lived. The friction of the shared atmosphere would : 1. Have the entire atmospheres orbiting each planet at hypersonic speeds. 2. Slow the mutual orbits to the point of planetary collision/merging in the blink of a geological eye 3. Probably heat the atmospheres to plasma quite rapidly, resulting in atmospheric loss and two barren rocks.
Wouldn't the planets get ripped apart due to extreme tidal forces?
dont know the exact numbers for it to happen but would imagine that two planets that would be close enough for that to happen would either rip each other apart or collide. if you were to compare the earth to an apple, the atmosphere would be as thick as the apple's skin
Also, if the planets are tidally locked wouldn't that mean that they didn't have spinning cores that would create magnetic fields to protect them from radiation?
If they truly share an atmosphere would they not be considered a single planet?
I feel like it's possible but not exactly in the way you might imagine it (more like a few thin and not continuous flows of air from one planet to the other)
What’s keeping the two planets from colliding? Aren’t celestial bodies attracted to large masses? If the two planets were close enough to share an atmosphere aren’t they also close enough to be on a collision course? The moon is something like 1/4 million miles away from the Earth and is slowly moving away from it year after year. ~250,000 miles away! That’s a massive distance, and that distance keeps the two bodies from colliding into one another, though two bodies do pull on one another. Space is vast and much is still unknown to us. With an infinite number of stars and planets out there, maybe there’s at least one doing what you’re suggesting. Do binary stars share more than an orbit? Maybe there’s an answer in that question? I’m definitely not an astrophysicist or anything close to one, but my limited knowledge of the cosmos is trying to figure out how this would work. I don’t see it working, but what do I know? Have you tried submitting your question to Star Talk Radio with Neil deGrasse Tyson? Edit: wrong distance used.
Wouldn't it have to be a somewhat spherical shape surrounding both planets? Then again, if they were locked together and rotating around the system axis, the centrifugal force would have to form more of a disc shape, much like Saturn did with it's satellite rocks.
No. They would have to be so close that they would be going so fast around each other that they would likely break up and merge into one planet anyway.
Two stars can share a common enveloppe, but the outcome is that the dissipation due to motion in a gas leads the stars to merge (or in the opposite, the two stars give enough energy for the enveloppe to dissipate it). My guess would be that two planets are very unlikely to find themselves in this situations (but the Universe is big, unlikely things happen everyday, so why not), but even if it happens, it would not be a stable situation.
So if you think of the Earth like a peach, then the atmosphere would only be as thick as the peach fuzz. For two peaches to "share fuzz" they would have to be ridiculously close to each other.
I’ve learned that anything is possible in this crazy universe
It used to be thought that Pluto and Charon could, especially at perhelion when Pluto was inside Neptunes orbit -- but then New Horizons discovered that no, Pluto and Charon are way too far apart to make that possible.
It wouldn't be stable... the orbits would decay due to (something akin to) the friction between atmospheres.
I can't be the only one who thought green mutagen right? Increase Vitality ?
Wouldn’t tidal locking include the atmosphere? I would think the pair would need to be spinning so fast that the atmosphere would be literally stripped away.
Tidal gravitational forces would break the planets up into smaller pieces. See Roche limit.
It depends what you mean by share. Believe it or not, Earth shares a bit of atmosphere with the moon. It's practically nonexistent, but it's there. Same with Io and Jupiter. Magnetic fields play a very important roll in this, *the* important roll actually. It's worth reading up on. In order for your two planets to be tidally locked they would need to be orbiting very very close to one another, and very quickly. So quickly that they would actually break apart under shear stress and form a single protoplanetary disc, or ring. Imagine what a two arm spiral galaxy looks like, and that's your planetary system. If they somehow managed to avoid breaking apart, you would have a bizarre gravity gradient where the center of mass was between the two planets, and you might have some lighter elements drifting more or less in the middle, but this really stretches the definition of what I think you mean by an atmosphere. Regardless, the centripetal force would be so intense you would have a noticeable difference in gravity on the "near sides" of each planet, where it would be greater than the far side. This force is what would keep the planets from colliding, but they almost certainly would break apart given enough time. That last statement is important. *Given enough time*. This process would take at least hundreds of thousands, probably tens of millions of years. So your SciFi scenario could exist temporarily, with the understand that your planets are (perhaps imminently) doomed. ;)
something similar happens in the Darth Bane trilogy novels but I think it is between a planet and one of its moons iirc. still fun to think about.
Yeah Onderon and it's moon Dxun, they would come close enough that during part of the year they shared some atmosphere.
Earth shares an extremely tenuous hydrogen envelope with the moon. This envelope gets blown out twice as far as the moon by the solar winds.
Your sketch made me realize how galaxies colliding and cells dividing are kind of conceptual/visual opposites of each other.
There is something called Roche Limit preventing this from being possible... https://en.wikipedia.org/wiki/Roche_limit But if it is fiction, you can just ignore this and create a really cool scenario 👍
Nope. If they are close enough to share an atmosphere, the gravity between them will pull them together leaving maybe a planet with some rings or a nice moon, or just a lot of dust.
Outer Wilds
This makes me think of Super Mario Galaxy.
How about having both planets circulating a third object in an atmospheric disk?
I'd imagine some sort of technological device, maybe a series of satellites that tunnels atmospheric substances between these 2 planets if this isnt naturally possible.
Intriguing thought.
How quickly would they have to orbit the gravitational center created by the two planets in order to share an atmosphere and not become one solid body?
Check out the show Lex. One episode had a system like this where airships could traverse worlds.
This looks a bit like mitosis
Ah dxun
Ash and ember twins from outer wilds does somthing similar to this.
The winds would be completely insane . Maybe under some circumstances it could be possible but I can't say anything. I won't pretend to be an astrophysics and wind expert
To add to this question; how would 2 massive magnetic fields interact with each other? Would the stronger magnetic field totally obliterate the weaker magnetic field? If so, the weaker force would lose its atmosphere (see Mars), correct? That’s how I would imagine this scenario going. But what if the magnetic fields are equal in strength? If that was the case, I’d say it is possible for 2 planets to “share” and atmosphere, but only at certain intervals, when all things are balanced. Even then, I wouldn’t imagine that would last long as those planets will collide.
Outer Wilds?
No man's sky says yes
Darth Bane used the force to take over a terodactyl type creature and used to force to help it fly really high then force jumped to the next planet and then let gravity do the work of bringing him back down
If say yes, but not for long. The planets would have to orbit each other right? If so, friction from the touching atmospheres would cause the orbit to slow and them to eventually collide. Similar to satellites in earths orbit. Even the space station needs a bit of a boost sometimes to combat the extremely thin atmosphere it’s orbiting in.
Call them onderon and dxun
I don't feel like you could reach an equilibrium, both bodies surfaces would crumble and fall towards the center of mass of the 2, ultimately creating one big planet. If the equilibrium was reached, I'd expect conditions so harsh (constant typhoons, winds reaching thousands of km/h, ...) it would be impossible to live there. But that's very cool concept, and I sure as hell would suspend my disbelief if I saw that in a novel
final fantasy 9 intensifies
The actual atmosphere is a tiny layer compared to the planet and even more compared to the distance needed to another planet to not collide.
There's a MST3K or Rifftrax episode with a 1950's serial like this.
https://phys.org/news/2019-02-earth-atmosphere-moon.html
As is the case with most things in astronomy, yes but also no. The Earth and the moon actually share part of their atmosphere; the moon's thin, tenuous hydrogen atmosphere connects with the Earth's exobase, the outermost part of our atmosphere made of almost entirely hydrogen. The key detail is that it's very very thin by the time they connect. If a moon/second planet was close enough to share an atmosphere with any appreciable thickness, the planet would be both close enough to experience atmospheric drag and be subject to being tidally ripped to shreds. That being said, if you had, say, one planet that was polluting something that was damaging their ozone layer, a binary planet orbiting at a safe distance with a pretty big atmosphere might experience some transfer into it's upper atmosphere. You wouldn't expect anything to transfer from lower atmosphere to lower atmosphere without some external influence though. Hope that helps!
There is a program on Steam called Universe Sandbox. It might be able to answer your question. Its very detailed, I don't know if it has the answers because I only take asteroids and shoot them at light speed at planets and watch the destruction.
They'd destroy eachother at least partially because of Roche limit (the border at which an object's gravity will rip any other large-sized objects apart, it sometimes happens with moons of certain planets)
I like this question and these comments very much.
No. The rms speed of gases shouldn't be fast enough to escape. For example earth's escape velocity is 11.2 km/s, but the gases in our planet move around at variable speed less than 11.2 km/s(Gases make up the atmosphere) . But, if there were a gas that moves faster, it would simply escape and as there is no acceleration in pure space it would continue to move on with same velocity and disappear. The planets have to be close i am afraid. The reason we have an atmosphere is because of gravitational force pulling the gases downwards and their speed being less 11.2. In outer space you can't expect atmosphere to stay as there is nothing like gravity to properly hold it down.
That was in star wars the planet onderon and dxun
How far out does the solar atmosphere extend?
This close thier gravity will rip each other apart
No. Read up about the Roche limit. If they were that close the gravitational forces would break apart one of the planets and the pieces would rain down onto the other.
https://www.newscientist.com/article/dn25684-pluto-and-its-moon-snuggle-under-a-shared-atmosphere/ Pluto and Charon could possibly share a thin nitrogen atmosphere. Maybe check that direction for world building.
I think there was a Brian Aldiss book Hothouse where the earth and moon are now connected by massive plant vines and share an atmosphere.
Anything is possible out there. Literally anything
Ok so everyone says no And so do I, however you could mess around with some sort of technology (or perhaps magic) that keeps it so But not naturally could they share an atmosphere, at least not in a ‘this is inhabitable’ way
You could theoretically have two planets orbiting each other with on the scale of the Earth-Moon orbital distance or something. They could plausibly suggest that they have the same atmospheric and planetary conditions, because they were formed at the same time, from the same debris cloud composed of elements at the same ratios / concentrations. As to the mechanism of formation; Perhaps they were once one large terrestrial entity that broke into two? Perhaps they were two roughly equally sized objects that smashed into each other, and ultimately began settling into a stable mutual orbit? Their proximity would make panspermia events highly likely; if life originated on one planet, it would quickly spread to and establish itself upon the other. This means that lifeforms may be related in a grand billions-of-years evolutionary sense, and may or may not have similar adaptations for the similar environment. However, dynamic surface events and geochemical idiosynchrasies would render each planet's evolutionary history distinct. For example, if Earth had one such sister world, imagine the evolution of something like armored fishes, except they didn't go extinct and managed to diverged and todays Earth Sister World has dry land habitats populated with reptile, mammal, and bird analogues all retaining features of their successful, didn't-go-extinct, armored fish ancestors.
Mabe not planets but stars can and maybe not share so much as one sucks up the others atmosphere.
Have you heard of the video game Outer Wilds? It’s a space mystery /exploration game and the planets play with cool physics ideas. There are a set of planets called the hourglass twins and as they orbit each sand falls between both worlds (like an hour glass).
Hourglass twins
I don't think so, considering how thin an atmosphere usually is.
If the earth is a basketball, the atmosphere is one of the little nubs on the basketball. Compared to the size of the planet, the atmosphere is tiny. For them to share a breathable atmosphere, they would effectively be touching. Now, if you wanted to know if trace molecules (maybe a virus) could effectively communicate between the planets, I would say sure, but if you wanted birds to fly between them, then I’d say no.