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Hurried Thoughts: You're Wrong About Tidal-Locking

239 points by sohkamyung 3y ago

mistercow 3y ago
This seems to offer an interesting (partial) candidate for the Great Filter. What if there are tons of advanced civilizations on tidally locked planets orbiting red dwarfs, who have never reached for the stars, because they simply can’t see them? Or rather, they can see them only once they’ve developed the technology to explore a side of the planet which they’re extremely poorly adapted for. Imagine if we had only been able to even begin to study astronomy through polar expeditions, for example.
- bombcar 3y ago
  If we were tidally locked, and were about where we are now or a few centuries ago, there'd be tons of people trying to explore the "dark side of Earth" and they'd see the stars.
  - rini17 3y ago
    They likely don't have night vision, so they would need to use instruments. They can only discover stars (perhaps except few brightest ones) after invention of photography.
    - CuriouslyC 3y ago
      I think it's more likely that the interesting life would evolve from organisms that exist on the fringe and can survive and migrate to either side.
    - bluGill 3y ago
      Do they have fire? Clouds mean they already can adjust to different light levels - at least some. A fire lit torch is obvious if you have fire.
    - andrewflnr 3y ago
      "Night vision" is not a special binary adaptation. It's not as if humans have exemplary might vision either, and we see LOTS of stars in a dark sky. Plus there are lots of diurnal reasons to not be helpless in low light, like tree cover and caves.
      - XorNot 3y ago
        Probably more importantly, an obvious adaptation in such an environment for prey animals would be to hide in dark places like caves where predators can't see you...so predators would develop with low-light vision for hunting where other predators couldn't and in turn.... Basically evolution tends to do every weird thing it can - and we can't know which would be likely to end up as traits on the dominant intelligent species.
        rini17 3y ago
        Well, hiding under water is another obvious adaptation...but it does not automatically mean sea mammals evolved gills. They did evolve but in other ways. Some weird things just don't happen.
    - bombcar 3y ago
      They’d likely have discovered caves or roofs at some point - and have some ability to see in dimmer light.
- HPsquared 3y ago
  Not having celestial navigation would also make such exploration more difficult.
  - mistercow 3y ago
    Yeah, although given that ancient humans figured that out, maybe it wouldn’t take an advanced civilization very long. That’s probably the biggest flaw with the idea. Like, imagine a civilization at our stage, minus the stuff we learned by having a night sky (no universal gravitation; computers and radio, but no GPS; quantum physics but no general relativity, and so on). Now they manage to voyage into the cold, dark night. How quickly can they catch up? Decades maybe, but probably not centuries. I think the other question is cultural. How much do they _care_ about space, when even the basic concept is new and alien, and studying it is very expensive?
    - fnordpiglet 3y ago
      I’d note that navigation was most important on oceans while terrestrial navigation relied on landmarks and maps. I wonder though how much exploration helped lead to an advanced civilization. The exchange of ideas with different cultures was crucial as was the necessity to develop the technologies for exploration beyond navigation alone. It wasn’t until we broadly navigated the planet that we advanced so rapidly after tens of thousands of years of relatively isolated stagnation.
      - TheOtherHobbes 3y ago
        I have a theory that Western culture developed relatively quickly because the geography is basically easily-farmable land around an inland sea with plenty of islands which is easy to navigate and explore. The Egyptians and the Phoenicians lacked the easily farmable land. Greece was fertile but a little arid, Northern Europe was harsher and riskier, but Rome was in a perfect sweet spot. On the other side of the world China had the farmland but not the inland sea, so there was less motivation for sea-borne trade and exploration. So it all started with a tradition that required basic materials science, knowledge of the weather, currents, and seasons, navigation by the sky, and the politics of war and trade across large distances. And it didn't stop until we had explored the entire planet and taken the first steps into space. In between we had to learn about time, navigation, and planetary weather patterns, how to build and power better ships, and more complex politics. It seems like a very natural progression.
- Galaxeblaffer 3y ago
  Very interesting idea ! I do wonder though if sufficiently complex life would ever evolve in an almost completely stable climate.
  - johngossman 3y ago
    The tropics have more life and a more stable climate than the temperate regions. They also are warmer, so that’s not an argument that a stable climate is more amenable to life, but at least a hint it isn’t an overriding factor. I also realize that may not say much about the origin of complex life. Just trying to think of examples.
    - Ekaros 3y ago
      Not to forget deep sea is also very stable in temperature. Being function of denseness of water.
- johngossman 3y ago
  An even more extreme version of this is life in the seas under an ice world like Europa.
- otabdeveloper4 3y ago
  Hot take: the Great Filter is the fact that we're actually alone as an intelligent species in the universe. Occam's Razor and all that.
  - mistercow 3y ago
    That’s not an explanation. It’s a restatement of what the great filter is trying to explain.
    - otabdeveloper4 3y ago
      Occam's Razor says that we don't see any aliens because none actually ever exist. Anything else is, alas, wishful thinking.
      - root_axis 3y ago
        Occam's Razor would suggest we just don't have the technology to detect them, you'd need extra reasoning to explain why earth is unique among thousands of trillions of planets.
        otabdeveloper4 3y ago
        > ...you'd need extra reasoning to explain why earth is unique among thousands of trillions of planets It is unique by definition, because we happen to live on it. There is no need to reason or explain anything, because it is a simple fact.
        root_axis 3y ago
        That meaning of unique doesn't have anything to do with the conversation at hand.
      - mistercow 3y ago
        Again, that’s not an explanation. An explanation would explain why aliens don’t exist despite apparently ample opportunities for them to.
- lynx23 3y ago
  That sounds like a Greg Egan book yet to be written :-) I discovered that it is real fun to think about these things when I read Incandescence. BTW, I am taking recommendations for books similar to that one, it appears I love that subgenre.
- kjkjadksj 3y ago
  We’ve had to go up to snowy, oxygen depleted mountaintops to study our own astronomy too. For a while even such study was deemed heretical by the church. There are many potential filters to science. Many still in place with our own species today, even.
  - deleted 3y ago
    [deleted]
- klyrs 3y ago
  Life is attracted to gradients; I would expect the most interesting behavior at the twilit ring.
  - sfink 3y ago
    But the article's main point is that the intermediates/gradients in heat and moisture are not necessarily where you expect them to be. If you have a point heat source on one side of an enclosed volume—a big box, say—then in a vacuum the most "interesting" area is halfway between that point and the far wall. But if there's a gas or liquid in the box, convection will produce a flow where the interesting regions are scattered around and that midway point is probably one of the less interesting spots. Life is also attracted to energy. Even if it started in the twilit ring, it would compete to fill the most insolated areas, and would be lushest there. I think it's more like life is attracted to the volume of flow. A gradient is what drives the flow, but the flow has velocity and so sums up the gradient over a history of motion.
taeric 3y ago
Very fun article. I don't feel that I was "wrong" going in, as I had no real concept of most of this. I was definitely ignorant of a lot of scenarios, though. In particular, I knew the moon was tidally locked to the earth; but that was about as far as my thinking on that went. I'd somewhat assume that the moon is "swelled" towards the earth, but maybe not because then the sun would break the lock? The article covers that the general variables involved with moon orbits largely precludes this, I think. Would be a lot of fun to have a VR experience that lets you see some of this from the different perspectives.
- solardev 3y ago
  Don't know about VR, but Space Engine on Steam seems to have tidally locked planets... https://forum.spaceengine.org/viewtopic.php?t=206 https://forum.spaceengine.org/viewtopic.php?t=206
  - taeric 3y ago
    I doubted what I'm asking for exists, yet. Basically a "hands on" experience in the latest simulations we know. Always fun to see others are already there working on a lot of this.
jrd79 3y ago
Is it possible to collect actual observations to confirm or deny the results of this modeling? A key part of any well formed scientific hypothesis is that it can be validated or disproved by real world experimentation or observation (falsifiable). Where will that data come from in this case? Computer models are an important part of science, but if they can't be validated against data, what's the point?
- johngossman 3y ago
  One of the references has a section on Implications for Observations of exoplanets. https://iopscience.iop.org/article/10.3847/1538-4357/aa9f1f/meta#apjaa9f1fs5 https://iopscience.iop.org/article/10.3847/1538-4357/aa9f1f/...
- s1artibartfast 3y ago
  It seems quite falsifiable. We Just need to visit or image several hundred tidally locked planets in the habitable zone. Also, theory and models still have value in the absence of experimental data. They can inform your decisions on what experiments to run! They can also inform your decision on how to behave in the absence of data and validated models.
johngossman 3y ago
Count me as wrong. One of the things I learned about weather is that the winter cold is largely an effect of surface heat radiating into the sky at night. The paper indicates that atmospheric circulation is enough to compensate for that and keep the dark side warm. Not a climatologist: but how do you explain the Earth’s poles then? One of the charts shows the dayside average at 300K and night at 250K. That second number is warmer than our Arctic in winter.
- s1artibartfast 3y ago
  >One of the things I learned about weather is that the winter cold is largely an effect of surface heat radiating into the sky at night. I wouldnt say "largely". My understanding is that the hours of daylight is more significant than hours of night, though obviously related. A cursory review seems to indicate that daytime flux at the surface is on the order of +250 W/m^2, whereas nighttime flux is much lower ~ -50 W/m^2
  - o11c 3y ago
    Hm, but daytime flux is highly angle-dependent, whereas nighttime flux is angle-independent ...
    - s1artibartfast 3y ago
      Another way to think about it is that radiative surface cooling isnt just at night. a black body radiates continuously 24 hours a day. The only thing that changes throughout the day is the amount if inbound solar flux.
- Jerrrry 3y ago
  The poles receive sunlight at a near 90 degree angle, ignoring the axial tilt. Direct sunlight vs. spread over an area.
- throwuwu 3y ago
  On a tidally locked planet the polar region is effectively the terminator line. There is also a greatly reduced Coriolis effect due to the very slow rotation. The insolation of the day side is a lot higher as mentioned in the article and is continuous rather than intermittent. All of that would lead to increased convection. Imagine the difference between a kettle being heated on a burner vs a kettle being heated by a blowtorch that rotates around it. The behaviour of the fluid in each will be quite different. Not a perfect model by any stretch of the imagination but maybe more intuitive.
ak217 3y ago
This is a fascinating analysis, but it doesn't mention the magnetosphere. I'm an amateur, but my understanding is that tidal locking means effectively no rotation with respect to the aspect of the solar wind. No rotation means no coriolis. No coriolis means no dynamo. No dynamo means no magnetic field to protect the planet. No magnetic field means the solar wind will strip the atmosphere, no?
- hlava 3y ago
  Well, Venus doesn't generate its magnetic field via geodynamo. Instead, it has some sort of weak magnetosphere induced by the interaction of the solar wind with the planet's ionosphere. Also even without this magnetic field, I guess the volatile processes on the surface are enough to keep the atmosphere going.
- dakr 3y ago
  I was also wondering about the stellar wind stripping away the atmosphere. Planets close enough to their stars to be tidally locked will experience more stellar wind than those farther away and dwarf stars have more flare events than stars like our sun does, exacerbating the problem (plus flares can release a lot of high energy photons, which can break apart structures like DNA).
- sfink 3y ago
  Yeah, that seems to be the elephant in the room. It's great that planets tidally locked to a red dwarf can block the heat with clouds, and mix the heat around with their atmosphere and ocean. But if being stuck up against a star means their atmosphere will be stripped off, then there will be neither clouds nor wind to do any good. Then again: Mercury has a dynamo-generated magnetic field, yet has the thinnest atmosphere of all of our planets[1]. Venus does not have a dynamo-generated magnetic field[2], yet has an extremely thick atmosphere. So it's not totally cut and dried. And there's of course the possibility of life in subsurface water. If the atmosphere were stripped, must the planet end up dry? Subsurface oceans can still mix the heat around. It could be underneath crust or ice (though the low atmospheric pressure would probably eliminate any ice near the top, so if it's ice it's probably underneath a crusty layer). Could tidal forces themselves drag enough magma around to generate a magnetic field good enough for shielding? The Earth's magnetic field from ocean tides is 20000 times weaker than the main one[3], but that's based on ions dissolved in water pulled by a relatively weak tidal force. What's a few orders of magnitude between friends? 1. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/planetary-magnetic-field https://www.sciencedirect.com/topics/earth-and-planetary-sci... 2. Venus has a small induced magnetosphere from solar wind hitting the ionosphere, but that's probably something that would lead to more loss, not less? 3. https://www.sciencealert.com/esa-swarm-satellite-map-ocean-tides-magnetic-field https://www.sciencealert.com/esa-swarm-satellite-map-ocean-t...
verisimi 3y ago
> I just figured it'd be nice to have a single relatively short place to address the most common myths about tidal-locked planets, and particularly their climate, for easy reference. Well that's nice and all, but this sort of explanation is hard to take! How can one verify that whatever-it-is about tidally locked planets, is not also a myth? Sure, these might be better set of guesses and assumptions, but it still cannot debunk myths. To see what I mean, I can debunk the idea that the gods live on top of Mount Olympus by climbing the mountain and checking. I can't check any of these potentially valid deductions. In fact, he could make the exact opposite points, and I would have no idea. None of us would.
- s1artibartfast 3y ago
  If someone trusted the old speculative models, they can choose to update to the new speculative models. If someone doesn't want to update their myth/model, who cares? Consensus and alignment don't matter. Even if you're wrong and you know it, there's no reason that should stop you from writing fiction the way you want.
adrynile 3y ago
i thought this was about the new DJ locks Tidal (the lame music service) put up. this is much more interesting :)
- jonathanlydall 3y ago
  I wonder if it’s like Spotify’s new AI DJ. Which I listened to for only 10s of minutes before it played a type of song completely unlike anything I’d ever listened to and would never listen to, at which point I was like “nope!” and I have no intent of trying it again. I also don’t care for DJ chatter, so didn’t like that, but if it helped me find more tracks similar to what I was listening to, I could live with it. What I want from my music streaming is a little bit of variety on what I already listen to. Essentially a huge shuffle list with occasional new tracks I can up or downvote, further training it on what kind of music I like.
  - pests 3y ago
    If you would have downvoted instead of leaving the Spotify AI DJ that's kind of how it works.
- risenshinetech 3y ago
  No you didn't. You just saw the worlds tidal and locking and figured you would make a cute comment about something clearly unrelated.
FranOntanaya 3y ago
I do remember Earth exceptionalism being pervasive, from the first satellite views of Mars up till maybe Galileo's pictures of Europa. Even today still get that feeling when it comes to the topic of liquid water, where people will point at the lack of meaningful atmospheres and declare places like Mars or any other body holding ices as too different to not be dry, when you just need the right ground temperature gradient and some trapped ice.
- bluGill 3y ago
  We don't really know what life requires. We know that earth has life. We have insufficient evidence for anyplace else (there is some evidence of life in our solar system but it could have been life that escaped our orbit by chance, or just contaminated sensors). All we have for sure is life exists on earth, so we know life exists on earth. Wikipedia has a list of other chemistries that could maybe support life, but we don't know if they do in the universe or not. We know that the basics of life on earth (water, carbon) are very common in the universe, and so there is no reason to think that life as we know it should be rare - but we also have no evidence of life elsewhere (mostly because we don't even have the ability to see evidence if it exists - the universe is large and we can't detect the important things even a few light years away)
  - mcmoor 3y ago
    And also that all our sister planets isn't like earth, and they all don't have life (as far as we observed). So it's another point for "not like earth"->"not have planet". Before those expeditions, we thought that fucking sun also has life on it https://adsabs.harvard.edu/full/2011JAHH...14..169C https://adsabs.harvard.edu/full/2011JAHH...14..169C
- GMoromisato 3y ago
  "Earth exceptionalism" is still the best answer to the Fermi Paradox. Maybe we're the first/only civilization in the galaxy. If so, then the question is, why? Maybe we're just the first and there will soon be millions of other civilizations. But most likely, Earth is a fluke. Either something in its environment made it conducive to civilization or some random (and rare) evolutionary path led to civilization. My uneducated guess is that microbial life is relatively common, but multi-cellular life is very rare and technological life is unique (at least in our galaxy).
at_a_remove 3y ago
I'm interested in that six image chart. The insolation seems high.
causal 3y ago
What an incredible blog. The pricing list on the left is particularly great - "want me to design a world for you? Here's a feature menu"
causal 3y ago
Fun to imagine how a tidally-locked civilization would grow up seeing a lot more symmetry in their environment than we do, and how their myths might spring up as a result. Also funny to imagine their scientists dismissing Earth as possibly habitable- "spinning around and around like that would result in impossibly complex weather systems - no way that's stable enough to sustain life!"
- rob74 3y ago
  What would be fascinating is imagining how the permanent daytime would influence their perception of time. The day is after all the fundamental unit of all human timekeeping, along with the seasons, and a tidally locked planet would have none of those. Maybe, if they are lucky, a moon big enough to be visible during daytime?
  - causal 3y ago
    Yeah! Also the mystery that the night-side of the planet would hold. If permanent cloud-cover for the day side holds true, then star-filled skies might just be a legend brought back by those who braved the darkness and lived to tell about it.
    - mangamadaiyan 3y ago
      Interesting parallels to Asimov's "Nightfall" there!
  - QuadmasterXLII 3y ago
    "Can a tidally locked planet have a moon" is a fascinating newtonian physics problem- I am thoroughly nerd sniped
    - saalweachter 3y ago
      Isn't that just Lagrange points?
      - 3y ago
bilsbie 3y ago
That’s great news. How cool it would be to visit such a planet.
egberts1 3y ago
Aw man, “tidality” is yet another variable that needs to be added on to the Drake Equation. (The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.) https://en.wikipedia.org/wiki/Drake_equation https://en.wikipedia.org/wiki/Drake_equation
- syncsynchalt 3y ago
  Covered in either n_e, f_i, or f_c I would think, depending on which of the three you're concerned that tides[1] or being tidally-locked would affect. [1] I mention tides because there are hypotheses that the presence of luna greatly contributed to abiogenesis and/or the mechanism by which life first left the oceans.
mlhpdx 3y ago
I like this refreshed model of the “eyeball” planet — perfect, endless beam reach sailing.
capitainenemo 3y ago
BTW, if the page author happens to be reading this. (loved the article BTW) Your header image Screenshot_15.png is 2½ megs in size which is pretty brutal on slower connections or for those with data costs. Plus it causes it to load a lot less snappily even on a decent connection. It is served in a fixed width 827px container yet is 1902px in size. Given the content (a simulated planet with fuzzy content) extra detail for HD isn't super useful and png will not compress well. Allowing for a little extra width for later retheming and then recompressing as jpeg... $ convert Screenshot_15.png -scale 1240x Screenshot_15_1240.png $ ~/hg/mozjpeg/cjpeg Screenshot_15_1240.png > Screenshot_15_1240.jpeg $ ls -l Screenshot_15_1240.jpeg -rw-r--r-- 1 nemo nemo 65870 Mar 7 13:55 Screenshot_15_1240.jpeg 2.6% the size of the original.
- kakkun 3y ago
  Also, there are some font size inconsistencies in the main body that should be looked into.
- wiredfool 3y ago
  My bank has a similarly sized png as the texture background of their pages, and sometimes it visibly, slowly, loads fresh on each page you go through.
- EvanAnderson 3y ago
  You're doing God's work. Thank you for caring.
  - gerdesj 3y ago
    Which God?
    - SturgeonsLaw 3y ago
      The God that was abandoned when Webmasters became Frontend Devs
- tux1968 3y ago
Razengan 3y ago
When I first played Monkey Island, the thing I oddly loved a lot about its world-setting was how some islands were perpetually in night and others in day. Of course that was a technical limitation and not an intended feature of the setting, but I always wondered how such a world might be possible. Now I have the answer. :)
867-5309 3y ago
imagine what tidal locking might do to the subterranean layers of a planet, compared to Earth's isotropic rotisserie
blackhaj7 3y ago
What a delight to read

239 points by sohkamyung 3y ago

This seems to offer an interesting (partial) candidate for the Great Filter. What if there are tons of advanced civilizations on tidally locked planets orbiting red dwarfs, who have never reached for the stars, because they simply can’t see them? Or rather, they can see them only once they’ve developed the technology to explore a side of the planet which they’re extremely poorly adapted for. Imagine if we had only been able to even begin to study astronomy through polar expeditions, for example.

bombcar 3y ago
If we were tidally locked, and were about where we are now or a few centuries ago, there'd be tons of people trying to explore the "dark side of Earth" and they'd see the stars.
- rini17 3y ago
  They likely don't have night vision, so they would need to use instruments. They can only discover stars (perhaps except few brightest ones) after invention of photography.
  - CuriouslyC 3y ago
    I think it's more likely that the interesting life would evolve from organisms that exist on the fringe and can survive and migrate to either side.
  - bluGill 3y ago
    Do they have fire? Clouds mean they already can adjust to different light levels - at least some. A fire lit torch is obvious if you have fire.
  - andrewflnr 3y ago
    "Night vision" is not a special binary adaptation. It's not as if humans have exemplary might vision either, and we see LOTS of stars in a dark sky. Plus there are lots of diurnal reasons to not be helpless in low light, like tree cover and caves.
    - XorNot 3y ago
      Probably more importantly, an obvious adaptation in such an environment for prey animals would be to hide in dark places like caves where predators can't see you...so predators would develop with low-light vision for hunting where other predators couldn't and in turn.... Basically evolution tends to do every weird thing it can - and we can't know which would be likely to end up as traits on the dominant intelligent species.
      - rini17 3y ago
        Well, hiding under water is another obvious adaptation...but it does not automatically mean sea mammals evolved gills. They did evolve but in other ways. Some weird things just don't happen.
  - bombcar 3y ago
    They’d likely have discovered caves or roofs at some point - and have some ability to see in dimmer light.
HPsquared 3y ago
Not having celestial navigation would also make such exploration more difficult.
- mistercow 3y ago
  Yeah, although given that ancient humans figured that out, maybe it wouldn’t take an advanced civilization very long. That’s probably the biggest flaw with the idea. Like, imagine a civilization at our stage, minus the stuff we learned by having a night sky (no universal gravitation; computers and radio, but no GPS; quantum physics but no general relativity, and so on). Now they manage to voyage into the cold, dark night. How quickly can they catch up? Decades maybe, but probably not centuries. I think the other question is cultural. How much do they _care_ about space, when even the basic concept is new and alien, and studying it is very expensive?
  - fnordpiglet 3y ago
    I’d note that navigation was most important on oceans while terrestrial navigation relied on landmarks and maps. I wonder though how much exploration helped lead to an advanced civilization. The exchange of ideas with different cultures was crucial as was the necessity to develop the technologies for exploration beyond navigation alone. It wasn’t until we broadly navigated the planet that we advanced so rapidly after tens of thousands of years of relatively isolated stagnation.
    - TheOtherHobbes 3y ago
      I have a theory that Western culture developed relatively quickly because the geography is basically easily-farmable land around an inland sea with plenty of islands which is easy to navigate and explore. The Egyptians and the Phoenicians lacked the easily farmable land. Greece was fertile but a little arid, Northern Europe was harsher and riskier, but Rome was in a perfect sweet spot. On the other side of the world China had the farmland but not the inland sea, so there was less motivation for sea-borne trade and exploration. So it all started with a tradition that required basic materials science, knowledge of the weather, currents, and seasons, navigation by the sky, and the politics of war and trade across large distances. And it didn't stop until we had explored the entire planet and taken the first steps into space. In between we had to learn about time, navigation, and planetary weather patterns, how to build and power better ships, and more complex politics. It seems like a very natural progression.
Galaxeblaffer 3y ago
Very interesting idea ! I do wonder though if sufficiently complex life would ever evolve in an almost completely stable climate.
- johngossman 3y ago
  The tropics have more life and a more stable climate than the temperate regions. They also are warmer, so that’s not an argument that a stable climate is more amenable to life, but at least a hint it isn’t an overriding factor. I also realize that may not say much about the origin of complex life. Just trying to think of examples.
  - Ekaros 3y ago
    Not to forget deep sea is also very stable in temperature. Being function of denseness of water.
johngossman 3y ago
An even more extreme version of this is life in the seas under an ice world like Europa.
otabdeveloper4 3y ago
Hot take: the Great Filter is the fact that we're actually alone as an intelligent species in the universe. Occam's Razor and all that.
- mistercow 3y ago
  That’s not an explanation. It’s a restatement of what the great filter is trying to explain.
  - otabdeveloper4 3y ago
    Occam's Razor says that we don't see any aliens because none actually ever exist. Anything else is, alas, wishful thinking.
    - root_axis 3y ago
      Occam's Razor would suggest we just don't have the technology to detect them, you'd need extra reasoning to explain why earth is unique among thousands of trillions of planets.
      - otabdeveloper4 3y ago
        > ...you'd need extra reasoning to explain why earth is unique among thousands of trillions of planets It is unique by definition, because we happen to live on it. There is no need to reason or explain anything, because it is a simple fact.
        root_axis 3y ago
        That meaning of unique doesn't have anything to do with the conversation at hand.
    - mistercow 3y ago
      Again, that’s not an explanation. An explanation would explain why aliens don’t exist despite apparently ample opportunities for them to.
lynx23 3y ago
That sounds like a Greg Egan book yet to be written :-) I discovered that it is real fun to think about these things when I read Incandescence. BTW, I am taking recommendations for books similar to that one, it appears I love that subgenre.
kjkjadksj 3y ago
We’ve had to go up to snowy, oxygen depleted mountaintops to study our own astronomy too. For a while even such study was deemed heretical by the church. There are many potential filters to science. Many still in place with our own species today, even.
- deleted 3y ago
  [deleted]
klyrs 3y ago
Life is attracted to gradients; I would expect the most interesting behavior at the twilit ring.
- sfink 3y ago
  But the article's main point is that the intermediates/gradients in heat and moisture are not necessarily where you expect them to be. If you have a point heat source on one side of an enclosed volume—a big box, say—then in a vacuum the most "interesting" area is halfway between that point and the far wall. But if there's a gas or liquid in the box, convection will produce a flow where the interesting regions are scattered around and that midway point is probably one of the less interesting spots. Life is also attracted to energy. Even if it started in the twilit ring, it would compete to fill the most insolated areas, and would be lushest there. I think it's more like life is attracted to the volume of flow. A gradient is what drives the flow, but the flow has velocity and so sums up the gradient over a history of motion.

taeric 3y ago

Very fun article. I don't feel that I was "wrong" going in, as I had no real concept of most of this. I was definitely ignorant of a lot of scenarios, though. In particular, I knew the moon was tidally locked to the earth; but that was about as far as my thinking on that went. I'd somewhat assume that the moon is "swelled" towards the earth, but maybe not because then the sun would break the lock? The article covers that the general variables involved with moon orbits largely precludes this, I think. Would be a lot of fun to have a VR experience that lets you see some of this from the different perspectives.

solardev 3y ago
Don't know about VR, but Space Engine on Steam seems to have tidally locked planets... https://forum.spaceengine.org/viewtopic.php?t=206 https://forum.spaceengine.org/viewtopic.php?t=206
- taeric 3y ago
  I doubted what I'm asking for exists, yet. Basically a "hands on" experience in the latest simulations we know. Always fun to see others are already there working on a lot of this.

jrd79 3y ago

Is it possible to collect actual observations to confirm or deny the results of this modeling? A key part of any well formed scientific hypothesis is that it can be validated or disproved by real world experimentation or observation (falsifiable). Where will that data come from in this case? Computer models are an important part of science, but if they can't be validated against data, what's the point?

johngossman 3y ago
One of the references has a section on Implications for Observations of exoplanets. https://iopscience.iop.org/article/10.3847/1538-4357/aa9f1f/meta#apjaa9f1fs5 https://iopscience.iop.org/article/10.3847/1538-4357/aa9f1f/...
s1artibartfast 3y ago
It seems quite falsifiable. We Just need to visit or image several hundred tidally locked planets in the habitable zone. Also, theory and models still have value in the absence of experimental data. They can inform your decisions on what experiments to run! They can also inform your decision on how to behave in the absence of data and validated models.

johngossman 3y ago

Count me as wrong. One of the things I learned about weather is that the winter cold is largely an effect of surface heat radiating into the sky at night. The paper indicates that atmospheric circulation is enough to compensate for that and keep the dark side warm. Not a climatologist: but how do you explain the Earth’s poles then? One of the charts shows the dayside average at 300K and night at 250K. That second number is warmer than our Arctic in winter.

s1artibartfast 3y ago
>One of the things I learned about weather is that the winter cold is largely an effect of surface heat radiating into the sky at night. I wouldnt say "largely". My understanding is that the hours of daylight is more significant than hours of night, though obviously related. A cursory review seems to indicate that daytime flux at the surface is on the order of +250 W/m^2, whereas nighttime flux is much lower ~ -50 W/m^2
- o11c 3y ago
  Hm, but daytime flux is highly angle-dependent, whereas nighttime flux is angle-independent ...
  - s1artibartfast 3y ago
    Another way to think about it is that radiative surface cooling isnt just at night. a black body radiates continuously 24 hours a day. The only thing that changes throughout the day is the amount if inbound solar flux.
Jerrrry 3y ago
The poles receive sunlight at a near 90 degree angle, ignoring the axial tilt. Direct sunlight vs. spread over an area.
throwuwu 3y ago
On a tidally locked planet the polar region is effectively the terminator line. There is also a greatly reduced Coriolis effect due to the very slow rotation. The insolation of the day side is a lot higher as mentioned in the article and is continuous rather than intermittent. All of that would lead to increased convection. Imagine the difference between a kettle being heated on a burner vs a kettle being heated by a blowtorch that rotates around it. The behaviour of the fluid in each will be quite different. Not a perfect model by any stretch of the imagination but maybe more intuitive.

ak217 3y ago

This is a fascinating analysis, but it doesn't mention the magnetosphere. I'm an amateur, but my understanding is that tidal locking means effectively no rotation with respect to the aspect of the solar wind. No rotation means no coriolis. No coriolis means no dynamo. No dynamo means no magnetic field to protect the planet. No magnetic field means the solar wind will strip the atmosphere, no?

hlava 3y ago
Well, Venus doesn't generate its magnetic field via geodynamo. Instead, it has some sort of weak magnetosphere induced by the interaction of the solar wind with the planet's ionosphere. Also even without this magnetic field, I guess the volatile processes on the surface are enough to keep the atmosphere going.
dakr 3y ago
I was also wondering about the stellar wind stripping away the atmosphere. Planets close enough to their stars to be tidally locked will experience more stellar wind than those farther away and dwarf stars have more flare events than stars like our sun does, exacerbating the problem (plus flares can release a lot of high energy photons, which can break apart structures like DNA).
sfink 3y ago
Yeah, that seems to be the elephant in the room. It's great that planets tidally locked to a red dwarf can block the heat with clouds, and mix the heat around with their atmosphere and ocean. But if being stuck up against a star means their atmosphere will be stripped off, then there will be neither clouds nor wind to do any good. Then again: Mercury has a dynamo-generated magnetic field, yet has the thinnest atmosphere of all of our planets[1]. Venus does not have a dynamo-generated magnetic field[2], yet has an extremely thick atmosphere. So it's not totally cut and dried. And there's of course the possibility of life in subsurface water. If the atmosphere were stripped, must the planet end up dry? Subsurface oceans can still mix the heat around. It could be underneath crust or ice (though the low atmospheric pressure would probably eliminate any ice near the top, so if it's ice it's probably underneath a crusty layer). Could tidal forces themselves drag enough magma around to generate a magnetic field good enough for shielding? The Earth's magnetic field from ocean tides is 20000 times weaker than the main one[3], but that's based on ions dissolved in water pulled by a relatively weak tidal force. What's a few orders of magnitude between friends? 1. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/planetary-magnetic-field https://www.sciencedirect.com/topics/earth-and-planetary-sci... 2. Venus has a small induced magnetosphere from solar wind hitting the ionosphere, but that's probably something that would lead to more loss, not less? 3. https://www.sciencealert.com/esa-swarm-satellite-map-ocean-tides-magnetic-field https://www.sciencealert.com/esa-swarm-satellite-map-ocean-t...

verisimi 3y ago

> I just figured it'd be nice to have a single relatively short place to address the most common myths about tidal-locked planets, and particularly their climate, for easy reference. Well that's nice and all, but this sort of explanation is hard to take! How can one verify that whatever-it-is about tidally locked planets, is not also a myth? Sure, these might be better set of guesses and assumptions, but it still cannot debunk myths. To see what I mean, I can debunk the idea that the gods live on top of Mount Olympus by climbing the mountain and checking. I can't check any of these potentially valid deductions. In fact, he could make the exact opposite points, and I would have no idea. None of us would.

s1artibartfast 3y ago
If someone trusted the old speculative models, they can choose to update to the new speculative models. If someone doesn't want to update their myth/model, who cares? Consensus and alignment don't matter. Even if you're wrong and you know it, there's no reason that should stop you from writing fiction the way you want.

adrynile 3y ago

i thought this was about the new DJ locks Tidal (the lame music service) put up. this is much more interesting :)

jonathanlydall 3y ago
I wonder if it’s like Spotify’s new AI DJ. Which I listened to for only 10s of minutes before it played a type of song completely unlike anything I’d ever listened to and would never listen to, at which point I was like “nope!” and I have no intent of trying it again. I also don’t care for DJ chatter, so didn’t like that, but if it helped me find more tracks similar to what I was listening to, I could live with it. What I want from my music streaming is a little bit of variety on what I already listen to. Essentially a huge shuffle list with occasional new tracks I can up or downvote, further training it on what kind of music I like.
- pests 3y ago
  If you would have downvoted instead of leaving the Spotify AI DJ that's kind of how it works.
risenshinetech 3y ago
No you didn't. You just saw the worlds tidal and locking and figured you would make a cute comment about something clearly unrelated.

FranOntanaya 3y ago

I do remember Earth exceptionalism being pervasive, from the first satellite views of Mars up till maybe Galileo's pictures of Europa. Even today still get that feeling when it comes to the topic of liquid water, where people will point at the lack of meaningful atmospheres and declare places like Mars or any other body holding ices as too different to not be dry, when you just need the right ground temperature gradient and some trapped ice.

bluGill 3y ago
We don't really know what life requires. We know that earth has life. We have insufficient evidence for anyplace else (there is some evidence of life in our solar system but it could have been life that escaped our orbit by chance, or just contaminated sensors). All we have for sure is life exists on earth, so we know life exists on earth. Wikipedia has a list of other chemistries that could maybe support life, but we don't know if they do in the universe or not. We know that the basics of life on earth (water, carbon) are very common in the universe, and so there is no reason to think that life as we know it should be rare - but we also have no evidence of life elsewhere (mostly because we don't even have the ability to see evidence if it exists - the universe is large and we can't detect the important things even a few light years away)
- mcmoor 3y ago
  And also that all our sister planets isn't like earth, and they all don't have life (as far as we observed). So it's another point for "not like earth"->"not have planet". Before those expeditions, we thought that fucking sun also has life on it https://adsabs.harvard.edu/full/2011JAHH...14..169C https://adsabs.harvard.edu/full/2011JAHH...14..169C
GMoromisato 3y ago
"Earth exceptionalism" is still the best answer to the Fermi Paradox. Maybe we're the first/only civilization in the galaxy. If so, then the question is, why? Maybe we're just the first and there will soon be millions of other civilizations. But most likely, Earth is a fluke. Either something in its environment made it conducive to civilization or some random (and rare) evolutionary path led to civilization. My uneducated guess is that microbial life is relatively common, but multi-cellular life is very rare and technological life is unique (at least in our galaxy).

at_a_remove 3y ago

I'm interested in that six image chart. The insolation seems high.

causal 3y ago

What an incredible blog. The pricing list on the left is particularly great - "want me to design a world for you? Here's a feature menu"

causal 3y ago

Fun to imagine how a tidally-locked civilization would grow up seeing a lot more symmetry in their environment than we do, and how their myths might spring up as a result. Also funny to imagine their scientists dismissing Earth as possibly habitable- "spinning around and around like that would result in impossibly complex weather systems - no way that's stable enough to sustain life!"

rob74 3y ago
What would be fascinating is imagining how the permanent daytime would influence their perception of time. The day is after all the fundamental unit of all human timekeeping, along with the seasons, and a tidally locked planet would have none of those. Maybe, if they are lucky, a moon big enough to be visible during daytime?
- causal 3y ago
  Yeah! Also the mystery that the night-side of the planet would hold. If permanent cloud-cover for the day side holds true, then star-filled skies might just be a legend brought back by those who braved the darkness and lived to tell about it.
  - mangamadaiyan 3y ago
    Interesting parallels to Asimov's "Nightfall" there!
- QuadmasterXLII 3y ago
  "Can a tidally locked planet have a moon" is a fascinating newtonian physics problem- I am thoroughly nerd sniped
  - saalweachter 3y ago
    Isn't that just Lagrange points?
    - 3y ago

bilsbie 3y ago

That’s great news. How cool it would be to visit such a planet.

egberts1 3y ago

Aw man, “tidality” is yet another variable that needs to be added on to the Drake Equation. (The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.) https://en.wikipedia.org/wiki/Drake_equation https://en.wikipedia.org/wiki/Drake_equation

syncsynchalt 3y ago
Covered in either n_e, f_i, or f_c I would think, depending on which of the three you're concerned that tides[1] or being tidally-locked would affect. [1] I mention tides because there are hypotheses that the presence of luna greatly contributed to abiogenesis and/or the mechanism by which life first left the oceans.

mlhpdx 3y ago

I like this refreshed model of the “eyeball” planet — perfect, endless beam reach sailing.

capitainenemo 3y ago

BTW, if the page author happens to be reading this. (loved the article BTW) Your header image Screenshot_15.png is 2½ megs in size which is pretty brutal on slower connections or for those with data costs. Plus it causes it to load a lot less snappily even on a decent connection. It is served in a fixed width 827px container yet is 1902px in size. Given the content (a simulated planet with fuzzy content) extra detail for HD isn't super useful and png will not compress well. Allowing for a little extra width for later retheming and then recompressing as jpeg... $ convert Screenshot_15.png -scale 1240x Screenshot_15_1240.png $ ~/hg/mozjpeg/cjpeg Screenshot_15_1240.png > Screenshot_15_1240.jpeg $ ls -l Screenshot_15_1240.jpeg -rw-r--r-- 1 nemo nemo 65870 Mar 7 13:55 Screenshot_15_1240.jpeg 2.6% the size of the original.

kakkun 3y ago
Also, there are some font size inconsistencies in the main body that should be looked into.
wiredfool 3y ago
My bank has a similarly sized png as the texture background of their pages, and sometimes it visibly, slowly, loads fresh on each page you go through.
EvanAnderson 3y ago
You're doing God's work. Thank you for caring.
- gerdesj 3y ago
  Which God?
  - SturgeonsLaw 3y ago
    The God that was abandoned when Webmasters became Frontend Devs
tux1968 3y ago

Razengan 3y ago

When I first played Monkey Island, the thing I oddly loved a lot about its world-setting was how some islands were perpetually in night and others in day. Of course that was a technical limitation and not an intended feature of the setting, but I always wondered how such a world might be possible. Now I have the answer. :)

867-5309 3y ago

imagine what tidal locking might do to the subterranean layers of a planet, compared to Earth's isotropic rotisserie

blackhaj7 3y ago

What a delight to read