[HN Gopher] Kepler telescope glimpses population of free-floatin... ___________________________________________________________________ Kepler telescope glimpses population of free-floating planets Author : jaytaylor Score : 154 points Date : 2021-07-06 16:45 UTC (6 hours ago) (HTM) web link (phys.org) (TXT) w3m dump (phys.org) | 0-_-0 wrote: | Can we use this data to calculate how many rogue planets per star | are in our galaxy? | actually_a_dog wrote: | This is expected to be the ultimate fate of the gas giants | (Jupiter, Saturn, Uranus, and Neptune) after the Sun leaves the | main sequence in about 5 billion years. Within 30 billion years | of the Sun becoming a red giant, Jupiter and Saturn are predicted | to fall into a 5:2 orbital resonance that destabilizes the | system, eventually causing all but 1 planet to be ejected within | 30 billion years. The remaining planet is expected to be ejected | within another 50 billion or so years.[0] | | So, within about 100 billion years, all that's going to be left | of our solar system is a white dwarf (which will likely survive | for trillions of years[1]), and 4 rogue planets, each drifting | alone in space. | | Somehow, I think this little story is more interesting than the | posted article, perhaps because it literally hits home. | | --- | | [0]: https://arxiv.org/pdf/2009.07296.pdf | | [1]: https://en.wikipedia.org/wiki/White_dwarf#Fate | ketanmaheshwari wrote: | Would time even make any sense given that we use the very | system to measure time. | klodolph wrote: | We stopped using the solar system to measure time a while | ago, and now use atomic clocks. Civil time is periodically | adjusted to match the rotation of the Earth, but the amount | of adjustment necessary is measured using atomic clocks, and | atomic clocks are still the basis of civil time. | actually_a_dog wrote: | Yes: | | > The second is defined as being equal to the time duration | of 9,19,26,31,770 periods of the radiation corresponding to | the transition between the two hyperfine levels of the | fundamental unperturbed ground-state of the caesium-133 atom. | | https://en.wikipedia.org/wiki/Second | | Unless the laws of physics aren't constant over very long | time periods for some reason, we could (if we were around to | do it) measure time 10^18 years from now just the same as we | do today. | lizknope wrote: | In Oklo, Gabon there was a natural nuclear fission reactor | about 1.7 billion years ago. The concentration of uranium | and groundwater was just right that nuclear fission | occurred naturally. | | We can measure the elements left behind and we have | determined that the fine structure constant was the same | then as it is now. | | If the laws of physics have remained constant for that long | then most scientists think they will remain constant in the | future. | | https://en.wikipedia.org/wiki/Natural_nuclear_fission_react | o... | actually_a_dog wrote: | Oh, sure, I wasn't saying the laws of physics were | _likely_ to change, simply that _if_ they did, the SI | definition of time might not be well posed. | | That said, although I agree the laws of physics are | likely to remain constant, 1.7 billion years is only just | about 12% of the age of the Universe. And, that time | period only reflects the most _recent_ 1.7 billion years. | So, there 's still some theoretical wiggle room there for | the fine structure constant to vary over time. After all, | heat death is not expected to occur for much more 100 | trillion years (if that is our ultimate fate)! [0] | | Edit: Come to think of it, if the laws of physics _aren | 't_ constant, how would it be possible to pose a coherent | definition of a unit of time at all? | | --- | | [0]: https://en.wikipedia.org/wiki/Future_of_an_expanding | _univers... | LeifCarrotson wrote: | In the sense that one second is 9,192,631,770 transitions | between two energy levels of the caesium-133 atom, no, | there's no change. 50 billion years is just shorthand for a | multiple of this number of transitions. International Atomic | Time, or TAI, is precisely defined for this kind of | measurement. | | Whether TAI is a fixed number of leap seconds away - | potentially billions - from UTC, is another question | entirely. If 'one day' is one rotation of the planet Earth | around its axis, and 'one year' is one rotation around the | Sun, and hours, minutes, and seconds are fractions of these | rotations, yeah, those cease to have much meaning when the | planet is swallowed up by and dissolved into the Red Giant | Sun's expanding chromosphere. | aquova wrote: | Assuming the gas giants remain roughly the same as they are | now, what would happen to them as they left the solar system | and the heat of the sun? Would the gases condense down turning | them from gas giants into rocky planets? | Tuna-Fish wrote: | Eventually, but it would take much, much longer than you'd | think. | | Jupiter, Saturn and Neptune all radiate ~2x the heat they | receive from the Sun. Most of their heat is primordial, | residue from the gravitational potential energy of all their | component parts falling together. A gas giant flung away from | it's host star will likely remain more or less as it is much | longer than the star is. | areoform wrote: | > Jupiter, Saturn and Neptune all radiate ~2x the heat they | receive from the Sun. | | As I've said elsewhere, this is most surprising for | Neptune, but the fact that these bodies radiate this much | heat is a clue that something more is going on. | | The primordial heat hypothesis doesn't hold up, as Uranus | was formed around the same time as Neptune and its energy | balance is 1.05. If the comparison is indeed accurate, then | the question remains what is making these planetary bodies | so hot? Neptune especially. | | Here are the energy balances of each to our best estimates, | | Jupiter, 2.132 +- 0.051 [current estimate, older estimate | was, 1.668 +- 0.085] (source, | https://www.nature.com/articles/s41467-018-06107-2#Sec2) | | Saturn, 1.78 +- 0.09 (source, https://www.sciencedirect.com | /science/article/abs/pii/001910... ) | | Neptune 2.61 +- 0.28 (source, https://agupubs.onlinelibrary | .wiley.com/doi/abs/10.1029/91JA... ) | | My tweets on the topic, | https://twitter.com/_areoform/status/1373376028861734918 | Tuna-Fish wrote: | > as Uranus was formed around the same time as Neptune | | [citation needed] | | There is clearly an unexplained anomaly vis-a-vis Uranus | and the other giant planets. But the closer you look at | them, the more weird Uranus appears. It would be amazing | if it turned out to be a much older planet captured by | our solar system. (That would certainly explain the | weirdo rotation...) | areoform wrote: | Here you go! | | https://books.google.com/books?id=RaJdy3_VINQC&pg=PA224&l | pg=... | | https://iopscience.iop.org/article/10.1088/0004-637X/789/ | 1/6... | | http://www.psrd.hawaii.edu/Aug01/bombardment.html | | For me the anomaly is the heat of these planets, and the | physical processes this suggests. I suspect that our | current explanations are only partial and that a great | discovery lies somewhere here. | actually_a_dog wrote: | Just to add on to this, NASA estimates that the internal | core temperature of Jupiter could be as hot as 24,000degK | [0]. For reference, the Sun's photosphere has a temperature | of about 6000degK [1]. | | --- | | [0]: https://www.nasa.gov/audience/forstudents/5-8/features | /nasa-... | | [1]: https://www.scientificamerican.com/article/i-read- | that-the-s... | Florin_Andrei wrote: | Okay, so as long as you have 3 or more bodies, I understand | ejection. Energy gets transferred semi-randomly such that | eventually one body gains too much energy and shoots out. | | But when N=2, what is the ejection mechanism? That's an | elliptical orbit that should be spinning round and round | forever (sans the losses via gravitational waves). | actually_a_dog wrote: | You mean how does the last planet get ejected? Well, that's | an interesting question, actually. Because of the inherent | stability of the 2 body system, the last planet gets ejected | some ~50 billion years after the others. | | The authors' simulation takes into account the fact that a | star comes close enough to the Solar System to have some | tangible effect every 23M years or so. It's the cumulative | effect of these stellar flybys that eventually nudges the | last planet out of the system. | ByThyGrace wrote: | > the fact that a star comes close enough to the Solar | System to have some tangible effect every 23M years or so | | Do you have a good source that expands on this? That sounds | so interesting. | Florin_Andrei wrote: | Ok, external perturbation, got it. | | Yeah, that makes sense. Otherwise it would just very slowly | spiral in, due to losses from general relativity. | actually_a_dog wrote: | Yep, and loss of angular momentum due to it being carried | away by gravity waves would probably take many trillions | of years, I would guess. | jcims wrote: | Understanding there's orders of magnitude of possible scale, | what's the likelihood that one of these passing through the | solar system would destabilize it enough to affect Earth? What | happens if it hits the sun? | vimacs2 wrote: | Very low but a more common and likely possibility is that it | could disturb the oort cloud and cause comets to fall in | system. Guess that could classify as what you are referring | to depending on your definition of solar system. | | A passing star is more likely to do this though and we | believe that they indeed have caused disturbances in our oort | cloud in the past. They might be potentially less numerous | than rogue planets as our universe ages but they have a far | larger potential hill sphere than even a very large planet so | interactions with neighboring stars' hill spheres are more | likely and frequent. | adolph wrote: | I've normally seen "oort" capitalized, so here is some | background if others have the same question as me. | | _The Oort cloud ( /o:rt, U@rt/),[1] sometimes called the | Opik-Oort cloud,[2] first described in 1950 by Dutch | astronomer Jan Oort,[3] is a theoretical[4] concept of a | cloud of predominantly icy planetesimals proposed to | surround the Sun at distances ranging from 2,000 to 200,000 | au (0.03 to 3.2 light-years).[note 1][5] It is divided into | two regions: a disc-shaped inner Oort cloud (or Hills | cloud) and a spherical outer Oort cloud. Both regions lie | beyond the heliosphere and in interstellar space.[5][6] The | Kuiper belt and the scattered disc, the other two | reservoirs of trans-Neptunian objects, are less than one | thousandth as far from the Sun as the Oort cloud._ | | https://en.wikipedia.org/wiki/Oort_cloud | alistairSH wrote: | It was not very long ago that I realized the outer bounds | of our Oort cloud are actually closer to Alpha Centauri | (4.25 light years away) than the sun. | | The scale of the universe never ceases to elicit feelings | of existential dread. | actually_a_dog wrote: | The outer edges of the cloud seem to be at ~100K AU [0], | while the a Centauri system is ~268K AU from us [1]. NASA | also gives the same number [2] for the distance to the | edge of the cloud. So, it looks like the Cloud extends | _almost_ halfway to a Centauri, but not that it 's | "closer to a Centauri than us"). | | As for the scale of the Universe: | https://htwins.net/scale2/ | | --- | | [0]: https://en.wikipedia.org/wiki/Oort_cloud#/media/File | :PIA1704... | | [1]: https://imagine.gsfc.nasa.gov/features/cosmic/neares | t_star_i... | | [2]: https://solarsystem.nasa.gov/solar-system/oort- | cloud/overvie... | actually_a_dog wrote: | This sounds reasonable to me, assuming Mercury didn't | either fall into the Sun or hit Venus. However, from the | perspective of Earth, we might not notice this much, due to | the effect of Jupiter (usually) either flinging comets away | from us, or actually absorbing the impact of the comets. | actually_a_dog wrote: | Ejection of the gas giants doesn't even take place until | after the Sun has gone into its red giant phase. The Sun will | swell so much that it engulfs the inner planets (Mercury, | Venus, Earth, Mars), so, Earth won't even be around to become | destabilized. | | Interestingly, the paper I linked talks about Mercury having | a 1% chance of becoming unstable _before_ the Sun enters its | red giant phase: | | > The mechanism forthe onset of Mercury's instability is well | understood: by virtue of locking into a linear secular | resonance with theg5mode of the solar system's secular | solution, Mercury's eccentricity can attain near-unity | values, resulting in a collision with the Sun, or even Venus. | Intriguingly, General Relativistic effects factor into this | estimate, with ancillary apsidal precession providing a | stabilizing influence on Mercury's orbit. | | If Mercury collides with the Sun, not much interesting will | happen. Mercury doesn't have enough mass to disrupt the | center of gravity of the Solar System when it falls into the | Sun, so, all that will happen is that the planet will get | vaporized, and the Sun will become infinitesimally more | enriched in metals. If you were around to witness the event, | it might be _visually_ spectacular, but not particularly | significant with respect to the fate of the system itself. | | They go on to say: | | > Within the context of this narrative, however, the | remaining planets appear unaffected and are currently | expected to remain stable for a lower limit of 10^18 years, | when diffusion arising from the overlapping mean motion | resonance of Jupiter and Saturn are expected to decouple | Uranus. | | This analysis, however, is reflective of older studies, which | don't take into account certain factors that this paper does. | kjs3 wrote: | _If Mercury collides with the Sun, not much interesting | will happen._ | | Yeah...but if it hits Venus...... | twiddling wrote: | If they are in a pentagon formation then it is simply the | Puppeteers | CodeGlitch wrote: | So it's entirely possible for one of these rogue planets to cross | into our solar system and disrupt the stable orbits of any | planet, including earth or the moon... | actually_a_dog wrote: | Sure, but a rogue planet would be far, far less disruptive than | a star coming near enough to us to affect the Solar System. | Such stellar flybys, according to a paper I linked in a | previous comment, occur every ~23M years, and are, indeed, | expected to act as a destabilizing force on the Solar System | over long periods of time. | cletus wrote: | The prospect and opportunity of rogue planets is fascinating to | me. | | So I'm firmly in the camp that the speed of light is a hard limit | in the Universe. Any talk of wormholes, FTL and space folding | just seems like wishful thinking and the product of not | understanding the domain of functions (eg putting negative values | into mass or energy). | | Additionally there's macro evidence to this speed limit because | if it wasn't a limit it would make the likelihood of encountering | spacefaring civilizations that much more likely. | | So given this, it seems like traveling to other stars requires | some form of generational ship. And that seems like a problem | because the energy required is massive and that's even before you | get into issues of having reaction mass. There are workarounds | for this (eg space laser propulsion) but the problems seem... | significant. | | So, rogue planets. I wonder if the first vessel for interstellar | travel will in fact be some largish rogue body that visits the | Solar System. Even something 100km wide will contain a wealth of | raw materials that would otherwise be prohibitively expensive to | accelerate to interstellar speeds. | | And sure it might take 10,000 years or more for such a body to | travel to a nearby star but there's really not a lot of | difference between several centuries and 10,000 years. | | What's more, such travelers could likely seed other rogue bodies | they encounter along the way. | | Could this be the initial vector of interstellar colonization? | | As an aside, George RR Martin 40+ years ago wrote a book called | Dying of the Light. I really enjoyed it just for the concept. In | this book there are so-called Festival worlds. These are worlds | that wander between systems. When they approach stars they get | sufficiently warm and thaw out and may have oceans and | atmospheres in that time. People would build cities in that time | knowing it was all temporary. | avaldes wrote: | > As an aside, George RR Martin 40+ years ago wrote a book | called Dying of the Light. I really enjoyed it just for the | concept. In this book there are so-called Festival worlds. | These are worlds that wander between systems. When they | approach stars they get sufficiently warm and thaw out and may | have oceans and atmospheres in that time. People would build | cities in that time knowing it was all temporary. | | Wow so this could be the explanation for erratic seasons of | unpredictable duration in ASOIAF? | InitialLastName wrote: | Everything about ASOIAF can be explained by George RR | Martin's long career as a military science fiction author. | | How else could one be free to build a medieval fantasy world | so unburdened by historical realism? | the_af wrote: | Which long career as a military science fiction writer? | | I admit aside ASOIAF I haven't read much GRRM -- his | awesome _Sandkings_ short story, and his collaboration with | Lisa Tuttle, _Windhaven_ , and I'm aware of some of his | horror/fantasy fiction. | | Checking on Wikipedia I don't see a lot of military scifi | in the list... | kzrdude wrote: | There is no explanation for the erratic seasons. GRRM (just | like any storyteller) creates mystery and interest in his | world and fills in the details that are required, and not so | many of those that are not. | | This is something he is very aware of. He will tell you that | like any intriguing medieval world map, his world map also | has tall tales, mysteries and stories about foreign | countries, big monsters and weird men, lining the edge of the | map. | blacksmith_tb wrote: | Hitching a ride on a fast-moving extrasolar object passing | through sounds good, though it seems like finding one going the | right direction (and with enough time to get aboard) would be | tricky. I suppose once you landed on it you could try and alter | its course with mass drivers, but of course the more massive it | was, the harder that would be. | actually_a_dog wrote: | If such a rogue planet were the result of ejection from its | previous planetary system, I wouldn't expect that its speed | would much exceed its previous orbital velocity in terms of | order of magnitude. For reference, the orbital velocity of | Mercury is about 60km/s [0], which is about 130,000 mph, or | 2e-4*c. | | We'd certainly notice something as big as a planet coming at | us when it's at around the same distance as the Oort cloud, | which NASA says lies at a distance of at least 2000 AU [1], | or 3e12 km. Since it would take almost 1600 years to travel | 3e12 km at 60km/s, I would say we'd have a fair amount of | preparation time, even if my estimate for the body's speed | were off by a factor of 15. ;-) | | As for choosing your course, I would say if a rogue planet is | about to enter the Solar System, beggars can't be choosers. | | What I find more interesting is that in order for people to | live on or near such a planet, it would almost have to have | enough of its own internal heat to create temperatures | suitable for life. So, you're almost certainly _not_ looking | at a rocky planet with a surface. Therefore, you 'd want to | design your habitat to orbit or exist within the atmosphere | of a gas giant. To my knowledge, there hasn't been any | serious proposal for such a habitat, and I'm unaware of the | sci-fi perspective on this issue. | | Of course, the other issue is that at 2e-4*c, you're not | going anywhere very fast. :P | | --- | | [0]: https://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryf | act.... | | [1]: https://solarsystem.nasa.gov/solar-system/oort- | cloud/overvie... | eloff wrote: | What's the point of interstellar colonization? | | It's possible that will never be interesting to us given the | expense, time, and hardships involved. | | We have more than enough space and resources in this solar | system to support north of a trillion humans if we start | building space habitats. So even if we start procreating again | after our population is predicted to stabilize, we won't run | out of room here very easily. | | My feeling is our digital worlds will get so engrossing we will | turn our attention inwards rather than outwards. I don't think | that lends itself to either population growth or interstellar | colonization. | | If intelligent civilization is sufficiently rare, that could | easily explain the Fermi paradox. They're out there, just too | far away and too uninterested in expansion for us to meet. | m4rtink wrote: | Even digital worlds need power to run and mass for hardware | to run on. Eventually there will not be enough of that in | Solar System and you will have to expand. | | Also more source material from real world events could be | useful for bootstrapping. | benlivengood wrote: | > What's the point of interstellar colonization? | | Gamma ray bursts can probably take out a whole solar system. | So could rogue stars or black holes. I think humanity is neat | and want it and its descendents to survive until the heat | death, so interstellar colonization it is. | saiya-jin wrote: | We have the potential for greatness. If only we could | somehow tame the darker aspects of humans we would actually | deserve a fate like this and probably be able to do it (or | at least that's my wishful thinking). | | But yeah diversification at least 100 light years around in | neighboring systems would greatly increase our chances of | survival any kind of random brutal event (unless one of our | neighbors goes supernova). It will be more of a question of | survival rather than 'do we want to colonize that other | system' | shkkmo wrote: | I see two major dynamics that could drive interstellar | colonization: | | 1) Eccentricity and Boredom: I think that with a solar system | population in the trillions, you will inevitably have a | sufficient population of eccentrics to eventually launch | generational ships. This is especially likely if humanity | survivea long enough for the lifetime our own sun to present | a realistic limit on the survival of the species. | | 2) Eccentricity and Freedom: The major advantage of | interstellar colonization is distance from dominant power | structures in the solar sytem. I find it quite possible that | there could be societies that view fleeing the solar system | as their only path to survival as a cultural unit. | Sanzig wrote: | One of the interesting consequences of interstellar | colonization in a universe without FTL travel or | communication (which, by all indications, appears to be our | universe) is the sheer amount of cultural diversity it | would create. Even adjacent systems would have | communications round-trip times on the order of single- | digit years, and depending how far apart desirable systems | for colonization are it could even conceivably be decades | of round-trip comms lag to the nearest inhabited system. | Centralization becomes impossible, and star systems would | have only very weak cultural impact on their neighbors. | shkkmo wrote: | Interstellar trade of physical goods is quite impractical | without FTL. If there is interstellar travel for non- | colonization purposes it seems like the primary goal | would be to enable low-latency communication to | compensate for semantic/cultural drift that could | interfere with the efficacy of the high latency | communcations. | m4rtink wrote: | Not just cultural but also possibly biological/corporeal | diversity as the different cultrues start to adapt to | their specific local environments. | | The Orions Arm collaborarive hard SF universe has very | many first contacts due to this as as often two | civilisations of human origin that meet each other look | to each other totally alien (one can survive in liquid | methane, the other near stars in hard vacuum). They did | meet a few actual (and very unique) aliens but it took _a | lot_ of verification it 's not just another hyper adapted | modification happy ofshoot of humanity. :) | BurningFrog wrote: | You or I won't go on this trip, but I'm sure _some_ people | are crazy /bold enough to do it. | | And that's all it takes. | dave_sullivan wrote: | You would find "the transcension hypothesis" very | interesting, it's along similar lines to what you are | discussing. | pfdietz wrote: | > What's the point of interstellar colonization? | | The cheapest way to fully explore another stellar system is | probably colonizing it, so explorers can be manufactured in | situ. | thechao wrote: | We'll run out of _sun_ at some point, even though (most) of | the time left for the energetic universe is still available. | cletus wrote: | > What's the point of interstellar colonization? | | Ultimately it's to claim matter, which is the ultimate | limiting factor in how long a civilization lives. For | example, you talk about engrossing digital worlds. Well, | those worlds require energy and energy means matter. | | To be clear we're talking on truly staggering time frames | here where a trillion years is a mere blink of an eye [1][2]. | | [1]: https://www.youtube.com/watch?v=Qam5BkXIEhQ&t=107s | | [2]: https://www.youtube.com/watch?v=Pld8wTa16Jk&t=1108s | shkkmo wrote: | The most likely form of non-generational inerstellar travel is | finding high efficiency methods to accelerate ships to high | relatavistic speeds so that time dilation reduces the on-ship | time to sub-generation scales. | tempest_ wrote: | There is an interesting book called Lockstep that explores | how a civilization might work without light speed. | Essentially they have perfected cryogenic sleep and the | entire civilization moves in lockstep, sleeping for many | years between waking up which allows for ships to move | between. | | The book itself is only so so but the concept is interesting | non the less. | cletus wrote: | This sounds appealing but there are a couple of major | problems. | | The first is that you have to get to a significant percentage | of light speed for this to manifest itself. Even at 0.95c | time is only traveling at 1/3 of normal speed [1]. | | Second, the energy cost for this is truly mind-boggling. | Doing so when you carry the fuel seems highly impractical. | The best bet are laser highways [2]. But, you need to build | that first. | | The upper limit of laser propulsion isn't really high enough | for that level of time dilation. | | Third, traveling at these speeds makes any potential impact | within even a speck of dust potentially fatal. | | Lastly, fun fact: such a ship actually needs to be | aerodynamic. Why? Above 0.95c the drag of hydrogen atoms in | the interstellar medium will start to slow you down. | | [1]: https://www.fourmilab.ch/cship/timedial.html | | [2]: https://www.youtube.com/watch?v=oDR4AHYRmlk | Myto wrote: | You could get to the nearest star in a few years and to the | other side of the galaxy well within a human lifetime with | "just" constant 1 g acceleration. Obviously this is far | from easy but it doesn't seem like it is necessarily out of | reach given a few thousand more years of continued | technological development. | actually_a_dog wrote: | Yes, and there are at least 76 stars ( _i.e._ potentially | interesting destinations) within 100 light years of us | [0]. So, assuming you can set an arbitrary course at | 0.95c, and decelerate without turning the humans inside | your ship to organic goo, you can reach quite a few | interesting places. | | --- | | [0]: http://www.solstation.com/stars3/100-as.htm | aardvark179 wrote: | The quotes you put round just are doing a lot of heavy | lifting. If you had a perfect photon rocket you'd only | need 1000000000 kg of fuel for each kg of payload to do | 1g to the centre of our galaxy and slow down again. | | Okay, maybe you can use a laser or something so you don't | have to carry the fuel with you, but you'll still need a | staggering amount of energy because the rocket equation | is a harsh mistress, and the relativistic version is even | worse. | shkkmo wrote: | Absolutely, there are huge problems and it may not ever be | feasible. However, I find it far more likely that we will | find a way to solve these concerns than that we will | develop FTL travel. | m4rtink wrote: | The thing will also be a weapon of mass destruction of | plannet cracking potential, one "parking accident" away | from making planets uninhabitable. | | On the other hand a civilisation producing such things | should hopefully be technically immortal with lots of | distributed backups for each individual potentially | affected by such accidents & resources to fix up any | affected infrastructure. So still, totally worth it, go fo | it! :-) | | (Less advanced neighbors might still be a bit on the edge, | so please be considerate.) | abecedarius wrote: | Send a small autonomous robot; at the destination it builds a | high-bandwidth radio receiver and factories; then 'upload' | the colonists by radio. Much more practical if your | civilization is reasonably advanced. | m3kw9 wrote: | Imagine meeting one of these planets while travelling in space, | the entire planet all dark and you are ordered to investigate. | escapecharacter wrote: | https://en.wikipedia.org/wiki/Blindsight_(Watts_novel) | rusanu wrote: | also https://en.wikipedia.org/wiki/Dragon%27s_Egg | astrange wrote: | https://en.wikipedia.org/wiki/Flatlander_(short_story) | actually_a_dog wrote: | Also https://www.imdb.com/title/tt0572231/ ( _Star Trek: | Enterprise_ , "Rogue Planet") | krisoft wrote: | Sounds spooky, but when I try to imagine it my mind throws an | exception: In any non-imaginary scenairo you wont have enough | energy and reaction mass to match speed with the object. in | these scenarios "ordered to investigate" means that you will do | some neat observations as you and the object drifts by. And if | you have somehow enough energy to match the planet's speed then | you are basically a god and you don't really have much which | can spook you. | | While the story of squishy human meatsacks traveling in a tin- | can braving the surface of one of these would be a compelling | read it is not really realistic sadly. | dwighttk wrote: | Probably inadvertently click-bait title with "population" | ambiguity | hindsightbias wrote: | If the planet isn't bound to a star and is behind the lensing | object, what is illuminating the planet that it appears | optically? | | Wouldn't be completely dark? | goodcanadian wrote: | The planet is the lensing object. It causes a background star | to brighten slightly in a very characteristic way. ___________________________________________________________________ (page generated 2021-07-06 23:00 UTC)