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Kepler telescope glimpses population of free-floating planets
- CodeGlitch 5y agoSo 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 5y agoSure, 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.
- actually_a_dog 5y agoThis 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 https://arxiv.org/pdf/2009.07296.pdf [1]: https://en.wikipedia.org/wiki/White_dwarf#Fate https://en.wikipedia.org/wiki/White_dwarf#Fate
- jcims 5y agoUnderstanding 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 5y agoVery 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 5y agoI've normally seen "oort" capitalized, so here is some background if others have the same question as me. The Oort cloud (/ɔːrt, ʊərt/),[1] sometimes called the Öpik–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 https://en.wikipedia.org/wiki/Oort_cloud
- alistairSH 5y agoIt 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 5y agoThe outer edges of the cloud seem to be at ~100K AU [0], while the α 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 α Centauri, but not that it's "closer to α Centauri than us"). As for the scale of the Universe: https://htwins.net/scale2/ https://htwins.net/scale2/ --- [0]: https://en.wikipedia.org/wiki/Oort_cloud#/media/File:PIA17046_-_Voyager_1_Goes_Interstellar.jpg https://en.wikipedia.org/wiki/Oort_cloud#/media/File:PIA1704... [1]: https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_info.html https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_i... [2]: https://solarsystem.nasa.gov/solar-system/oort-cloud/overview/ https://solarsystem.nasa.gov/solar-system/oort-cloud/overvie...
- ketanmaheshwari 5y agoWould time even make any sense given that we use the very system to measure time.
- klodolph 5y agoWe 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 5y agoYes: > 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 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 5y agoIn 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_reactor#Relation_to_the_atomic_fine-structure_constant https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...
- actually_a_dog 5y agoOh, 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_universe#Degenerate_Era https://en.wikipedia.org/wiki/Future_of_an_expanding_univers...
- Florin_Andrei 5y agoOkay, 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 5y agoYou 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.
- Florin_Andrei 5y agoOk, 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 5y agoYep, and loss of angular momentum due to it being carried away by gravity waves would probably take many trillions of years, I would guess.
- ByThyGrace 5y ago> 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.
- aquova 5y agoAssuming 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 5y agoEventually, 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.
- actually_a_dog 5y agoJust to add on to this, NASA estimates that the internal core temperature of Jupiter could be as hot as 24,000°K [0]. For reference, the Sun's photosphere has a temperature of about 6000°K [1]. --- [0]: https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-jupiter-58.html https://www.nasa.gov/audience/forstudents/5-8/features/nasa-... [1]: https://www.scientificamerican.com/article/i-read-that-the-suns-surf/ https://www.scientificamerican.com/article/i-read-that-the-s...
- hollerith 5y agoFor reference the temperature at the center of the sun is about 15 million °K
- perl4ever 5y ago>the Sun's photosphere has a temperature of about 6000° There was a paper that proposed that Earth's surface was about this hot for a while after the collision that formed the Moon. Even though the heat wasn't coming from nuclear fusion, for a while it was just as hot as a star, so the Moon, which was smaller and cooled faster overall, was remelted in places by "Earthshine" - therefore the discrepancy between the maria on the near side and the far side.
- perl4ever 5y ago>Within 30 billion years of the Sun becoming a red giant The Sun isn't expected to remain a red giant for 30 billion years, is it? More like a tenth of that, I thought.
- temporallobe 5y agoPlease forgive me, I am not a cosmologist, merely a humble software engineer - but your timespans of 30+ billion and into “trillions” of years seem awfully askew. The age if the entire universe is estimated at “only” 13.77 billion years old, so how is this possible? Are we simply in an extremely young universe?
- jhgb 5y ago> Are we simply in an extremely young universe? Well, in the set of positive reals, any number you randomly pick will be very small compared to the vast majority of all the numbers in the set.
- morpheos137 5y agoYeah because the age of the universe can't be negative.
- pieceoffeces 5y agoWho let you out of your cage? I thought lowlifes with enlarged brains weren't allowed out of their cells. dang, why did you give this human a pass?
- morpheos137 5y agoIs this the reddit culture infecting hn the other poster was complaining about? Stop being a little brother. cf 1984.
- tbabb 5y agoYes, by our current cosmological models, we are in a very young universe. We don't really know, but it may be the case that the universe is only conducive to life during this phase of its existence.
- XorNot 5y agoSee also: it's quite likely that no red dwarf anywhere in existence has run out of fuel, yet - some are estimated to last as long as 10 trillion years.
- cletus 5y agoThe 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.
- eloff 5y agoWhat'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.
- m3kw9 5y agoImagine meeting one of these planets while travelling in space, the entire planet all dark and you are ordered to investigate.
- escapecharacter 5y agohttps://en.wikipedia.org/wiki/Blindsight_(Watts_novel) https://en.wikipedia.org/wiki/Blindsight_(Watts_novel)
- rusanu 5y agoalso https://en.wikipedia.org/wiki/Dragon%27s_Egg https://en.wikipedia.org/wiki/Dragon%27s_Egg
- astrange 5y agohttps://en.wikipedia.org/wiki/Flatlander_(short_story) https://en.wikipedia.org/wiki/Flatlander_(short_story)
- actually_a_dog 5y agoAlso https://www.imdb.com/title/tt0572231/ https://www.imdb.com/title/tt0572231/ (Star Trek: Enterprise, "Rogue Planet")
- krisoft 5y agoSounds 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.
- m4rtink 5y ago
- dwighttk 5y agoProbably inadvertently click-bait title with “population” ambiguity
- hindsightbias 5y agoIf 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 5y agoThe planet is the lensing object. It causes a background star to brighten slightly in a very characteristic way.
- twiddling 5y agoIf they are in a pentagon formation then it is simply the Puppeteers
- 0-_-0 5y agoCan we use this data to calculate how many rogue planets per star are in our galaxy?
- spindle 5y agoIANAA, but I believe we already had a very rough estimate, from our models of solar system formation, and it's huge - at least tens of billions and very likely much more.
- peter_d_sherman 5y ago>"Tantalizing evidence has been uncovered for a mysterious population of "free-floating" planets , planets that may be alone in deep space, unbound to any host star. The results include four new discoveries that are consistent with planets of similar masses to Earth, published today in Monthly Notices of the Royal Astronomical Society. The study, led by Iain McDonald of the University of Manchester, UK, (now based at the Open University, UK) used data obtained in 2016 during the K2 mission phase of NASA's Kepler Space Telescope. During this two-month campaign, Kepler monitored a crowded field of millions of stars near the center of our Galaxy every 30 minutes in order to find rare gravitational microlensing events. The study team found 27 short-duration candidate microlensing signals that varied over timescales of between an hour and 10 days. Many of these had been previously seen in data obtained simultaneously from the ground. However, the four shortest events are new discoveries that are consistent with planets of similar masses to Earth. These new events do not show an accompanying longer signal that might be expected from a host star, suggesting that these new events may be free-floating planets. Such planets may perhaps have originally formed around a host star before being ejected by the gravitational tug of other, heavier planets in the system." PDS: Absolutely, utterly fascinating! Dare we dream that there are other free-floating planets like Earth -- somewhere else in the Universe? Perhaps we do after this discovery!