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Interstellar Visitor Found to Be Unlike a Comet or an Asteroid
- TangoTrotFox 8y agoThis article is excellent. I wondered about this exact issue before. Prograde/forward acceleration only from outgassing from a constant surface just seemed difficult to visualize. It would make some sense for an object with minimal spin since the side facing the sun would heat up more than the rest of the surface and so you'd have an outward acceleration primarily from the rear, but when you're spinning how could the outgassing not also [strongly] affect that spin, excepting some highly improbable scenario where your axis of spin is directly perpendicular to the sun and the 'thing' is perfectly balanced, like a propeller facing the rear of a plane? I also wish more media ran articles like this. It's fun to let your imagination run wild, apply a bit of math and visualization, and also learn lots in the process. And there's no division. Even if somebody says something completely wrong, people can have fun correcting and adjusting their views like a collaborative project instead of some competition to 'prove' your subjective interpretation right, as so many other topics devolve into.
- sjclemmy 8y agoI'm still convinced this is an alien probe. I mean look at that trajectory. 0.163 AU from Earth - what are the odds? The spinning is irrelevant surely - I mean, it's all relative, so as far as ’Oumuamua is concerned, we're spinning. Maybe it was spinning that way to stay aligned with a distant companion for communication.
- szilardboy 8y agoWhat’s special about 0.163 AU? Does it have a mathematical significance?
- inevitable2 8y agoAU stands for Astronomical unit, and it's used for measuring distances in space smaller than light-years. 1 AU is the distance between the Earth and the Sun. 0.163 AU tells you how close it came to earth.
- rbanffy 8y agoI'd prefer to use light seconds/minutes for that. Not only it's easier to grasp (0.163 AU seems awfully close, but 81 light seconds sounds reassuringly far) but it'll probably be more helpful when we have to communicate across these distances.
- azernik 8y agoJust that it's unusually close.
- RobertoG 8y agoAs we are in paranoid mode (and it's fun to be, isn't it?): not only it's unusually close, but it seems that Earth is the planet it pass closer in all the Solar System. Maybe somebody should check if that "slightly acceleration" bring it closer or farther to Earth. Maybe we have been photographed. I hope it's not that somebody shoot us and failed.
- ssijak 8y agoAliens got us just before GDPR, sneaky bastards!
- dwaltrip 8y agoThere is a bit of sampling bias, given that we are looking for space objects from Earth, and so it easier to detect something that comes closer to Earth. Not sure how significant the bias is for an object of this size and speed, but I'm guessing that it is probably a relevant factor.
- interfixus 8y agoTwo more of them, and I'd say you have an excellent case.
- lawlessone 8y agoThey do everything in threes.
- dboreham 8y agoA Arc, B Arc...
- pilsetnieks 8y agoIf one were so inclined, they could argue that the spinning is in fact very relevant, as it would allow a static camera or other observation device a full 360° view along all axes.
- rbanffy 8y agoAny civilization capable of building an interstellar craft would certainly have mastered the ability to move a camera by then ;-)
- pilsetnieks 8y agoStealth. If you wanted to reveal yourself, you wouldn't need to disguise your probe as space debris.
- gmt2027 8y agoIf you're right about the spin for alignment, we should be looking into deep space in the direction of it's axis. Presumably, this direction is erratic but there may be orientations that dominate over time. A tumbling probe that doubles as a cosmic pointer to home. Cool.
- p2detar 8y agoThis has always fascinated me. We can actually build giant spaceships (space stations) inside asteroids and use them for interstellar travel. All the resources we need, including ice would be at our disposal. Like traveling with your own mini-planet. Dirk Schulze had taken that as a subject into his sci-fiction book - Alien Encounter.
- huhtenberg 8y agoFor the book, the reviews on Goodreads aren't very good :-/ https://www.goodreads.com/book/show/18268008-alien-encounter https://www.goodreads.com/book/show/18268008-alien-encounter
- p2detar 8y agoThat's true, but I personally found it pretty engaging. In fact, I read the last 150+ pages in one night. I'd give it at least 4 stars.
- tomp 8y agoFrom an energy perspective, it's likely better to build your own station (from an asteroid - or alternative, remove all the mass from the asteroid that you don't need) - that way, you're only accelerating exactly the mass that you need, not wasting any energy accelerating the rest of an asteroid.
- neuronic 8y agoI think he is talking about chilling on the asteroid while it follows its known trajectory undisturbed, simply because they are packed with useful resources we can gobble up while waiting. Asteroid are per definition not interstellar though (until Oumuamua?).
- rbanffy 8y agoAn interesting approach would be to send an automated ship builder robot fleet to dismantle an asteroid and board the fully furnished ship when it makes another close approach, and then boosting it to its final destination. I'd love to see a scenario where we'd build robot terraforming fleets that'd land on an uninhabited planet, make it habitable, complete with spaceports, cities, factories, crops (all permanently tended for robots), build a couple extra fleets and launch to their next most promising targets. And then, for some reason, humans lose interest in all that and someone else wakes up to find a universe full of 60's futuristic utopian planets nobody ever lived in.
- jobigoud 8y agoThe odds we expect depend on our detection ability. Maybe there are thousands of these objects but we saw this one only because it passed so close to Earth.
- walrus01 8y agoThere is fairly strong consensus in the astronomy community that possibly hundreds of Sednoid class objects exist, and those are in relatively normal orbits compared to things which are beyond solar escape velocity. But so far we've only found 3 or 4 Sednoids. https://en.m.wikipedia.org/wiki/Sednoid https://en.m.wikipedia.org/wiki/Sednoid
- hannasanarion 8y agoSednoids orbiting in the kuiper belt are totally different from extrasolar objects on hyperbolic trajectories. Oamuamua passed inside Mercury's orbit.
- walrus01 8y agoYes, but both classes of objects are very dificult to detect, due to distance, size and lack of brightness. We only detected the extrasolar object once it had already passed perihelion and was on its way out.
- mbel 8y ago"Such an intrinsically faint body could be discovered only thanks to the close Earth flyby in October 2017, which created a tremendous opportunity for the first detailed characterization of a minor object of exosolar origin." https://arxiv.org/ftp/arxiv/papers/1712/1712.00437.pdf https://arxiv.org/ftp/arxiv/papers/1712/1712.00437.pdf
- w1nt3rmu4e 8y agoI prefer a complementary theory -- that it's a spent stage of a multi-stage spacecraft. If the primary stage were decelerating for a rendezvous with Earth, then any stage that made it to full acceleration would reach us first, probably getting close and then flinging back out of the solar system, just like this did. Easy enough to test -- we'll eventually see another object following the same trajectory, give or take, but that's decelerating. (Cue the dramatic music.)
- chimprich 8y ago"And on far-off Earth, Dr. Carlisle Perera had as yet told no one how he had wakened from a restless sleep with the message from his subconscious still echoing in his brain: The Ramans do everything in threes."
- turbo_fart_box 8y agoGreat series of books! Every time I see a thread about this big rock I think of Rama.
- interfixus 8y agoBeg to differ. Great book. Awful cheap hacks posing as sequels. I regret reading them - they've nearly ruined the original for me.
- notsofastbuddy 8y agoThe final reveal was mind-numbingly bad.
- rbanffy 8y agoMy personal theory is that Clarke's writing partners sedated and tied him inside a closet until the book was finished. That's the only way to explain how awful some of his last books were. Having said that, I liked Richter 10. Too bad the co-author died before they could write another one.
- mattlondon 8y agoLooking at the images on that site, the trajectory doing a "fly by" of a lot of the planets did look remarkedly like the sort of thing we've being doing for decades in our own solar system [1]- line up a bunch of planets and use gravity slingshots to do a close fly-by to get a closer look. The thought makes me have goose-bumps. Did some alient race just take a close look at us? Was there a voyager-style plaque on it? I guess we'll never know now. Occam tells us that in reality it is most likely just some space debris from some ancient rock-smashing incident, but the fact that this thing continues to defy classification allows us some space to imagine! 1 - https://duckduckgo.com/?q=voyager+gravity+slingshot+diagram&iar=images&iax=images&ia=images https://duckduckgo.com/?q=voyager+gravity+slingshot+diagram&...
- godshatter 8y agoI wonder if it's speed increased on it's way out. Maybe it's on a multi-system route, using gravity assist as it goes to cut the route time down by a few thousand years here or there as it circles back around to it's home system. Must be very patient aliens, assuming no FTL messaging tech.
- planteen 8y ago> 0.163 AU from Earth - what are the odds? Look at it from a sampling bias perspective. The object at its brightest was very dim (19th magnitude) and moving fast. The ability for rapid, repeating full sky surveys is recent (PanSTARRS had been online for around a decade). The limiting magnitude of PanSTARRS is 24th. So if such other such objects exist, of course we are going to find the closest ones first since they are the brightest.
- deleted 8y ago[deleted]
- TangoTrotFox 8y agoThere's another little fun point here. If this was a probe, the point where you'd accelerate to have the greatest effect on your trajectory would be exactly where it did - at one of its semi-major points - where its trajectory turns.
- jimijazz 8y agoI want this to be an alien ship so badly!
- tonmoy 8y ago> The spinning is irrelevant surely - I mean it’s all relative That is incorrect. All motion is not relative, only intertial motion is relative. Spinning implies acceleration on a body which is measurably different from any reference frame compared to a body that is not accelerating
- sjclemmy 8y agoWhat I meant was, the origin of the object may have been in a different inertial frame of reference to our solar system, so the 'spin' as far as it is concerned is not spin.
- burke 8y agoThis is not a thing though. Spin is spin, regardless of reference.
- sjclemmy 8y agoI really misunderstand my relativity then.
- wcoenen 8y agoYou seem to know that the rules of physics should hold in any inertial (i.e. non-accelerating) reference frame. But the thing you missed is that a spinning reference frame cannot be inertial. There is centripetal acceleration when something spins.
- justinpombrio 8y agoYou've got the right general idea, but the principle of relativity only applies to constant velocity motion. If two astronauts float past each other in space, either of them can claim that they're motionless and the other is moving past them. However, if one of them is accelerating or spinning, they'll both agree on who it is. https://en.wikipedia.org/wiki/Principle_of_relativity https://en.wikipedia.org/wiki/Principle_of_relativity https://en.wikipedia.org/wiki/Inertial_frame_of_reference https://en.wikipedia.org/wiki/Inertial_frame_of_reference
- jakeinspace 8y agoHow could spinning rapidly possibly help for communication? Unless this distant companion is moving at many times the speed of light in a massive ellipse. Also, as someone else mentioned, rotational motion isn't intertial, it's not just relatively different from us on Earth.
- tantalor 8y ago> what are the odds? 100%, because it happened
- xrayzerone 8y agoI'll ask what everyone is thinking but won't say. If the acceleration is in fact being caused by artificial thrusters, what kind of thruster configuration can produce prograde acceleration while maintaining the observed tumble? And why would someone engineer this configuration?
- kranner 8y ago> And why would someone engineer this configuration? To make its being engineered seem implausible, surely.
- Cthulhu_ 8y agoYou're saying instead of magic cloaking devices, the aliens used camouflage? Makes sense to me!
- dsfyu404ed 8y agoBecause it wasn't an important project so they made the fresh put of college ME do it.
- TheOtherHobbes 8y agoIt's maybe worth pointing out the tumbling is a hypothesis used to explain variable brightness measurements and not something that was observed directly. https://arxiv.org/pdf/1712.00437.pdf https://arxiv.org/pdf/1712.00437.pdf For all anyone knows the intrinsic brightness was variable. (This is probably not very likely without some supporting spectroscopic anomalies. But still.) As for thrusters - that's the same problem as the comet and outgassing hypothesis. No known mechanism can explain the acceleration. And if you were alien race and wanted to look at a planetary system without attracting attention, something that looks like a tumbling rock with a plausibly improbable trajectory would be ideal. It could just be a coincidence that the first large proven extra-solar object slingshotted around the Sun in a way that happened to pass close by the Earth. But considering the size of the Solar System and the convenient phasing of the Earth's orbit, what are the odds? It's certainly very curious.
- 8y ago
- drwasho 8y ago’Oumuamua, I’ve come to bargain!
- goatlover 8y agoThere was no other way.
- santoriv 8y agoBased on the comments in this thread, I'm sure this will soon be an episode of 'Ancient Aliens' on the "History" Channel. If it isn't already.
- goatlover 8y agoHow Oumuamua inspired the Egpytians to use logs and slave labor to build stone pyramids, like any advanced ancient alien would.
- newnewpdro 8y agoIt's too bad we're not ready to launch probes to visit and explore such transient objects at a moment's notice.
- _ph_ 8y agoI think it would make sense to plan a probe mission where the probe would be put into storage to stand by for these kind of events. It would still be a challenge and might be impossible to find a launch window and reach the passing object in time, but it would be worth trying. Just imagine how tragic it would be, if an ancient artifact of an alien civilization drifts by earth and we don't manage to have at least a look at it.
- holografix 8y agoWouldn’t such an object be emitting radio signals that earth could receive?
- _ph_ 8y agoOnly if it is actively emitting them. So if the aliens sent an active probe, it might emit radio signals. But if it is some junk from an alien civilization, it would just be trash drifting by. It would still be increadibly interesting to catch such an artifact.
- scottlegrand2 8y agoJust another roadside picnic?
- newnewpdro 8y agoNot if it's something like another civilization's Tesla Roadster.
- _ph_ 8y agoRight. As unlikely it is to run on other civilizations remainders, there is quite some chance for future humans to have a surprise find of a 2008 Tesla roadster :)
- DaveSapien 8y agoWould gravitational pull account for the acceleration? Meaning if it were made (or part of it) of some very dense element like Iridium, there would be an unexpected attraction to our sun?
- gliptic 8y agoGravity doesn't work that way, I'm afraid, as Galileo demonstrated.
- Cthulhu_ 8y agoNope; gravity is very predictable and very constant (see also the difficulty in detecting gravitational waves), they calculated how much it should accelerate under influence of gravity and found the actual acceleration to be different. As for the unexpected attraction, as one of the moon astronauts displayed, objects of different mass are attracted (fall) equally quickly by gravity in a vacuum.
- DaveSapien 8y agoThanks for your comments, they have kicked me out of my head space. I suppose I got it into my head thinking of massive densities, like densities of neutron star. Anything dense enough to make a difference would be very loud and easy to spot... as I'm writing this, even if it were very dense. The effect would only be seen when it is much closer to another gravity well. Ok, how about this (I'm still stuck on this gravity idea), there is an unseen "cloud" of rock orbiting (very) slowly round the main body. Seemingly slowing down and accelerating as it orbits. A small body or cloud of bodies could easily be small enough for us to not see it, but enough to cause this effect. Sound reasonable?
- nrjames 8y agoThis reminds me of Rendevous with Rama, which I’m currently reading with my daughter.
- divbzero 8y ago’Oumuamua’s “mysterious thrust” [1][2] is obviously from rocket thrusters which undoubtedly come in threes. 1: [’Oumuamua] was being slightly accelerated by an unseen force, which they argued could only be attributed to comet “outgassing” acting like a thruster. 2: Now in a new study that is currently under peer review, Roman Rafikov, an astrophysicist at the University of Cambridge, argues that the same forces that appeared to have accelerated ’Oumuamua — the same forces that should have also produced a tail — would have also affected its spin. In particular, the acceleration would have torqued ’Oumuamua to such a degree that it would have spun apart, breaking up into smaller pieces. If ’Oumuamua were a comet, he argues, it would not have survived.
- yitchelle 8y agoI am truly surprise that we don't get more interstellar visitors into our solar system. It kind shows how small our solar system is, or other way, how big the universe is.
- ianai 8y agoWe could have many more and not know. This one was seen because it came so close to the earth.
- kidsnow 8y agoWe have telescope technology to thank. The quality and the number of telescopes is constantly increasing. We don't just look in the sky any more, we watch the same spot over time and look for changes. We are seeing more spots, more time, and more changes. An investment in telescopes is an investment in physics.
- jimijazz 8y agoI wouldn't be so sure we don't... Just because we don't see them with our 5 senses doesn't mean they are not here yet.
- krapp 8y agoYou do realize we're not limited to "our 5 senses" when studying the universe, right?
- jimijazz 8y agoYou're totally right. I actually didn't think of that, but just meant that maybe other forms of being could exist and manifest in dimensions we're not even looking at. Is that why my comment was downvoted?
- ceejayoz 8y agoThere's a good chance these sorts of things are whizzing past us all the time, and we're just not detecting them. I mean, we just discovered ten new moons of Jupiter this year: http://earthsky.org/space/10-new-moons-discovered-jupiter-1-oddball http://earthsky.org/space/10-new-moons-discovered-jupiter-1-...
- xab9 8y agoThe Dig comes to my mind from 1995.
- artificial 8y ago“I miss you too darlin’...” such an epic soundtrack. Bah, I gotta listen to it now!
- deleted 8y ago[deleted]
- InclinedPlane 8y agoThis is a little misleading because it presents the idea that there is a firm separation between "comets" and "asteroids", each of which have very different properties. In reality we've discovered in recent decades that there is significant overlap. Pure comets were formed in the outer solar system beyond the frost line, and they are composed of a mixture of primarily chondritic grains and ices. As noted such bodies are not very structurally strong so if they approach the Sun too closely they will break up from the stress of gravity as well as from the intensity of off-gassing vaporizing gasses. On the other hand you have classic asteroids which are formed inside the frost line and are made up of either chondritic material, stone, or metal (depending on their histories). Such asteroids can be much stronger but they lack the ices which might off-gas during a close solar encounter. Except, that dichotomy is a simplified fiction. The reality is that there are objects in the middle, sometimes called "iceteroids" which we've discovered over the years. These could be the cores of comets which have lost most of their ices or these could be objects with more complicated histories, such as asteroids which have accreted surface layers of ices through various processes. So this is a mystery but it's not some enormous mystery it's a small mystery. The idea that an asteroid could have acquired a small amount of ices on its surface isn't exactly world shattering news but because we don't know the history of the object we don't know the process by which it ended up with its observed properties.
- Balgair 8y agoTo me, the interesting thing is that this iceteroid (love the term!) is definitively extra-solar and that means that it is likely that other systems have both asteroids and comets. Though we've seen asteroids in other systems like Fomalhaut [0], we've not been up close and personal with the compositions of extra-solar material. Here in the Sol system, we have a pretty strange arrangement of planets [1], with big ones all in the outer system and smaller ones in the inner system. So looking at just our system is not very indicative of 'typical' system evolution, in terms of iceteroids. Once we figure out where Oumuamua came from, that'll give us some idea of the compositions and evolutions of other systems (data point of 1 is better than 0), like the frost line. Oumuamua should be viewed as awesome and exciting, but as the tip of the ... iceberg ... when it comes to the real questions of stellar evolution and all the awesome stuff happening there. [0]https://en.wikipedia.org/wiki/Fomalhaut https://en.wikipedia.org/wiki/Fomalhaut [1]https://en.wikipedia.org/wiki/Nice_model https://en.wikipedia.org/wiki/Nice_model