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Our Solar System Is Even Stranger Than We Thought
- ryanackley 8y agoMy first thought is this should call into question the method(s) we are using to measure and observe planets in other solar systems. Think on this, the one solar system we can empirically confirm with multiple observation techniques, i.e. we've sent satellites to other planets in, is way different than solar systems we are observing by measuring light differences from light years away.
- bpicolo 8y agoKeep in mind that this isn't true for every system they've detected, it's just more likely than not given current examples - 909 planets in 355 systems according to the abstract: http://iopscience.iop.org/article/10.3847/1538-3881/aa9ff6/meta http://iopscience.iop.org/article/10.3847/1538-3881/aa9ff6/m... There's plenty of differences from our own solar system out there that also don't fit that pattern. Gas Dwarfs are a planetary type that we don't have in our own solar system, for example: https://en.wikipedia.org/wiki/Gas_dwarf https://en.wikipedia.org/wiki/Gas_dwarf
- 0-_-0 8y agoYes but the solar system is a biased sample: life evolved in it. Maybe it was helped by Jupiter shielding us from asteroids that could wipe out life on the planet? If it's statistically more likely that intelligent life evolves in a system with large planets then we would expect to see a difference between our solar system and others that we observe.
- kamaal 8y agoAll asteroid crashes aren't equal. Earth got most of its water from an asteroid crash. Basically a huge of range of things have to work on large timescales for intelligent life to evolve on a planet. Which is why intelligent life apart from us could just be absent or very very rare and far away.
- celrod 8y agoThe article discusses an "oligarch" model of planet formation, where there are roughly early sized and spaced oligarchs early on in planet development. Because our solar system didn't end up with the "peas in a pod" pattern, planet formation they also posited a period of violent collisions that stirred things up. Wild, uneducated, and necessarily oversimplifying speculation: perhaps all these early collisions brought water which helped encourage development of life, and led to the formation of Jupiter, which then protected that life's development.
- 0-_-0 8y agoMy point is that a large planet in the system reduces the probability of large asteroid impacts later in a star system's history. I didn't mean that it immediately removes all asteroids from a star system after forming.
- kamaal 8y agoTrue, but you need water rich asteroids to crash in the immediate phases after planet formation, and then you need life to develop. After which you need asteroids to not crash into the planet. Of course in the meanwhile, you need a lot of other things like formation of atmosphere, plate tectonics, volcanic eruptions, lakes sitting on geysers etc etc. Basically things have to (not) happen in a series of steps for life to form, even if other things like a rocky planet being situated in the goldilock zone come true. This is apart from a lot of other factors, like not having a big sun etc etc. All this suggests even if we consider 'Terrestrial mediocrity' to be true. Life could just very very rare across the universe, if not totally absent.
- hypothete 8y agoThe "Jupiter as a shield" hypothesis has been questioned recently: https://phys.org/news/2016-02-jupiter-role-planetary-shield-earth.html https://phys.org/news/2016-02-jupiter-role-planetary-shield-...
- 0-_-0 8y agoThat's fair enough, the point I tried to make is: Statistically, we would expect our solar system to be average among solar systems that can support intelligent life, not among all solar systems (following the Anthropic Principle). Therefore, the difference we see between our solar system and the average star system might imply something about what kind of conditions make intelligent life more probable in a star system. If we see that in all star systems we know that evolved intelligent life (even if there's only 1 we know of) there is a large Jupiter-like planet, and that's very atypical among star systems, that suggests that Jupiter might have increased the probability that intelligent life evolved here.
- ryanackley 8y agoHow do you know the statistic probability of life evolving in a solar system? We don't have an observation technique to definitively observe this. Again, we've only ever observed a single solar system up close.
- memebox3f 8y agohttps://en.wikipedia.org/wiki/Anthropic_principle https://en.wikipedia.org/wiki/Anthropic_principle
- JoeAltmaier 8y agoYet, life here on earth has happened more than one way. Seems like its pretty hardy if one planet gets more than one start on life? Isn't that a statistic of sorts?
- memebox3f 8y agoThats not true is it? life on earth started more than once, source pls!!!
- noselasd 8y agoThere are currently no evidence that life on earth happened more than once.
- JoeAltmaier 8y agoHow about the multiple principles of life observable in what we see? Not just plants vs animals or fungi, Sulphur-based life chemistry, iron vs copper blood in higher orders and so on?
- 317070 8y agoCurrently, all life we know of fits into a single tree of life. All known lifeforms for instance agree on using RNA for something, hence the RNA world hypothesis. I would also be interested in a study which points to the opposite.
- kamaal 8y agoI always thought something so far away would appear to us as Pixels. Its kind of mind blowing, we have techniques both theoretical and practical to only see pixels and yet come up with their exact dimensions.
- dredds 8y agoWe don't usually detect them directly. We observe a star dimming (planetary transit) or wobble and infer the planet's location, speed, and mass from that. We are only just developing techniques to observe very large planets close to their sun directly by efficiently cancelling out the sun's light.
- kamaal 8y agoThat is precisely what is so interesting. Even a star wouldn't be anything more than a fat pixel, and the planet would be more like a thin pixel. Plus the star dimming, given the orbit would also be a long drawn phenomenon, like in case of earth(1 year). I understand we ideally decide these things based on color of the light we see. And light waves stretch as the distance increases, and it can all be figured out by doppler effect. But its still kind of mind blowing how much we can infer from just these things.
- netcan 8y agoFascinating stuff. ..and all deduced from the slightest dimming of starlight hundreds of light years away. Badass.
- Symmetry 8y agoThat's pretty comforting. As the solar system we live in seems more unusual it seems more credible that planets with advanced life might be rare. In which case the emptiness of the galaxy seems more explicable.
- jerf 8y agoPutting the Great Filter not merely behind us, but way behind us, would be a pretty cool scientific result.
- kijin 8y agoThere may be more than one Great Filter. We could have passed one of them, but we might not survive the next one.
- pc86 8y agoThe entire point of a "Great Filter" is that there is one that wipes out the majority of species that make it that far. If there are multiple then they're just likely cataclysmic events.
- Izkata 8y agoNo, the Great Filter is more general than self-destruction. Some examples I've seen of possible Great Filters we've already passed include: * The formation of any life at all * The jump from single-celled life to multi-cellular organisms * The ability to create/use/pass on knowledge of tools
- jerf 8y agoThe point of the Great Filter argument is that something seems to be preventing widespread intelligent life. If the Filter is behind us, then while that is not proof that there are no impassible obstacles in front of is, we have no particular reason to believe that there are impassible obstacles in front of us. That is in stark contrast to what has been the scientific dogma for the past several decades, which is that there is nothing special about us whatsoever, which does give us reason to believe there are impassible obstacles in front of us. To be able to put the filter way behind us is still a real change.
- sidcool 8y agoI am fascinated about how less we know overall about the earth, and the solar system. I would not be surprised if we found life in the solar system. May not be advanced, but multi cellular life. I mean life as it was on earth some 10,000 years ago, with early humans and all. Edit: Sorry I shared my fictitious fascination. It would probably make a good movie, humans finding pre-historic humans on Titan or Europa.
- lachlan-sneff 8y agoEarly humans were pretty damn advanced, at least in terms of biology.
- contravariant 8y agoI would be surprised if even our concept of cells translates that easily. Unless of course both forms of life share the same origin, but that just raises more questions.
- Balero 8y agoI think it might work quite well actually. They could certainly not work with any of the biological systems as ours, such as proteins and fats etc. But I think it is likely that there would be internal subdivisions in a complex life-form. This is however likening, branches in trees, to cells in an organism, to crystals in a rock.
- jerf 8y agoCells are a pretty fundamental structure. Sci-fi can have fun with undifferentiated masses of protoplasm like The Blob, but there's a lot of reasons to expect that cell walls are going to be pretty fundamental on one level or another. Without them, instead of isolating the task of giving permission to enter and exit the life form to one structure, everything in the life form has to be capable of doing so. It is exceedingly unlikely that this is a good trade. I would also say that before you start drawing up crazy ideas about alternate structures that you should check your own body first; we already have a lot of variants on the theme! Blood is a liquid that has a lot of cells in it. There's a lot of other such circulatory fluids that have cells within them, but are not "cellular" in the sense that they contain nothing but cells. White blood cells do interesting things with cell walls, as does the immune system in general. Cells have structure well beyond just little cubes already, like nerve cells, etc. Personally I find that when one tries to come up with some funny sci-fi idea for an alternate life form, either A: it's physically implausible or B: something, somewhere on Earth is already doing something very like it, and I don't see middle ground very often.
- perseusprime11 8y agoThe thought of we may be the only species in the Universe scares me. And, we don't have a great insurance policy.
- pc86 8y agoNot being the only species is equally frightening.
- digitalsushi 8y agoIt is far, far more frightening to consider we are all alone, given our modern understanding of scope, statistics, and molecular biology. Maybe we are all alone! But that's way more terrifying because not only are we alone, but it's just damned irregular from what we might expect.
- Brockenstein 8y agoI can't believe that we're alone, even if intelligent life is extremely rare, and life in general somewhat rare. It's a big universe. Or is it just as terrifying to be First?
- bluGill 8y agoRegardless of the truth, for practical purposes we are alone. The speed of light is far to slow on the scale of even the galaxy (must less universe) to do anything useful about any intelligent life that might be there.
- nikbackm 8y agoWhy? All of us living now will be long dead before our species die out, so what difference does it really make?
- revscat 8y agoBecause not all of us are so selfishly narcissistic and are rather able to consider the effect upon the lives, extant and not yet born, of our current decisions. Your apparent lack of empathy, and similarly our cultural worship of selfishness and self-deception, are foul clues as to our eventual doom. If choices today are critical in determining the viability of human life over the next several decades, but those choices conflict with the selfish wants of children in the present, and those present-day children choose to disregard future generations, then what hope do we have? The Great Filter for our species is capitalism.
- qubax 8y agoStranger? We already knew our solar system was strange. At least compared to the other solar systems we observed ( admittedly a tiny fraction - a couple hundred out of 200 billion solar systems ). We already knew gas giants ( a major cause of our peculiarity ) are rare. And we knew that most solar systems had uniform sized planets ( within a particular range ) orbiting very close to their suns. The article doesn't offer anything new that would make us think the solar system is stranger. It just reaffirms everything we knew and why we thought it was strange to begin with.
- deleted 8y ago[deleted]
- ncmncm 8y agoNot convincing. We know Kepler results are heavily biased for (1) systems edge-on to us (2) with big planets (3) very close to their star. The only conclusion to draw is that planets that are all clustered close to their star tend to similar sizes. Then only Mercury is unusual. Even there, it's not unique. Stars with planets distributed more widely, like ours, have been systematically filtered out of the results. We have no idea how common they are. It might be that they are rare, and that would make us unusual. In that case, distribution would be interesting and relative sizes would be unremarkable. If in fact they are common, there is no reason to expect sizes in those cases to be uniform. A system that condensed from a cloud with less intrinsic rotation seems more likely to have its planets clustered close. Less intrinsic rotation could also result in more uniformity.
- vanderZwan 8y ago> We know Kepler results are heavily biased for (1) systems edge-on to us (2) with big planets (3) very close to their star. This article was written by an astronomer working with Kepler, and I wonder why you apparently seem to believe that they are so naive that they forget about the bias in their own research tools. Furthermore, the article explicitly mentions this issue, and provides an explanation for why they believe it does not apply, making me wonder if you read it at all: > I concocted (on my laptop) imaginary planetary systems in which the sizes of planets orbiting a given star were random. Could some sort of bias in Kepler’s method of finding planets—which favors the detection of large planets close to their stars—contrive to make the planets in each of my imaginary systems appear to fit the pattern? The answer was no: in more 1000 trials with randomly assigned planet sizes put through a virtual Kepler’s detection scheme, a pattern of similarly-sized planets in the same systems never emerged. Unless you have a reason to dispute this method of verification of course, but then you should share that. I personally see no problem: the claim is implicitly that since the measured data does not match the predictions of the model, the model is wrong. The model + known bias of Kepler is used in simulation to generate expected statistical output of measured data sets. The generated data does not match the measured data. Hence, either the model of Kepler's bias is wrong, or the model of what planetary systems to expect. Since we based the planetary system model on our own solar system, if that model is wrong then that makes our own solar system special.
- thrower123 8y agoI don't stay up on the latest developments in this field day to day, but my understanding is that most of the extrasolar systems that we can observe are a little on the wonky side to begin with, otherwise we wouldn't be able to detect that there are planets in them at all. Super-Jupiters orbiting close enough to make their stars wobble, binary star systems, all kinds of stuff. I'm not sure I'd hazard a guess at any kind of definite conclusion at the makeup of the universe and our overall specialness in it, with tools of observation as crude and limited as we've still got; there's a long way to go just to survey what is out there.
- dwaltrip 8y agoI believe the article attempts to account for your concern.
- orbitingpluto 8y agoHumanity has only been searching for exoplanets for a very short time. That's why there are relatively few candidates farther than 1 AU out. It's somewhat like arguing that all lattes are comprised of milk only because we've only taken the first sip.
- spectre256 8y agoI'm not sure why you were downvoted, that's a beautiful analogy.
- KnightOfWords 8y agoThe author may well have found a real pattern, but it may only apply to a subset of planetary systems. Kepler is biased towards detecting large planets with short orbital periods. Perhaps tightly packed systems have similar sized planets because this is a more stable arrangement. However, more widely spaced systems - which we have far less data on - may not show this pattern. We're learning something here but we don't really have enough information to know how remarkable our solar system is.
- dgudkov 8y ago
- dugluak 8y agoapologies if this is a stupid question, but I always wondered can there be multiple objects/planets in an orbit?
- dbh937 8y agoLangrangian points L4 and L5 are stable places where objects can orbit ahead of and behind a larger one, like a planet: https://en.wikipedia.org/wiki/Lagrangian_point https://en.wikipedia.org/wiki/Lagrangian_point Asteroids occupying these spaces in our solar system are called Trojans: https://en.wikipedia.org/wiki/Trojan_(celestial_body) https://en.wikipedia.org/wiki/Trojan_(celestial_body)
- saalweachter 8y agoThe short answer is "yes", but the longer answer is "we haven't observed this happen in practice for any significant planetoids". There was an observation five or ten years back that originally looked like it might be two planets in the same orbit, but it turned out that one planet was in an orbit with a period exactly twice that of the interior planet.
- hoorayimhelping 8y agoNot a stupid question at all. The answer is: yes. https://en.wikipedia.org/wiki/Trojan_(celestial_body) https://en.wikipedia.org/wiki/Trojan_(celestial_body) Theories for the formation of our moon suggest a Mars-sized Trojan collided with earth before it was earth: https://en.wikipedia.org/wiki/Theia_(planet) https://en.wikipedia.org/wiki/Theia_(planet)
- deleted 8y ago[deleted]
- dredds 8y agoThey recently announced the first detection of an exo-moon, but said the moon was the same size as the Earth (orbiting a much larger gas planet) so the definition of planet and moon is blurry. Unfortunately the terms 'dual-planets', 'double-planets', or 'binary-planets' are not (yet) recognized by the International Astronomical Union (IAU) according to wikipedia.
- vanderZwan 8y ago> To test whether the peas-in-a-pod pattern was real, I concocted (on my laptop) imaginary planetary systems in which the sizes of planets orbiting a given star were random. Could some sort of bias in Kepler’s method of finding planets—which favors the detection of large planets close to their stars—contrive to make the planets in each of my imaginary systems appear to fit the pattern? > The answer was no: in more 1000 trials with randomly assigned planet sizes put through a virtual Kepler’s detection scheme, a pattern of similarly-sized planets in the same systems never emerged. This computational experiment did not reproduce what we observe in the Kepler planetary systems. Thus, the regular sizes of planets is a real astrophysical pattern. This is actually a really cool use of computer simulations that I haven't noticed before (but I'm sure has been done in the past): simulating expected output for a known bias. I wonder if it would be feasible to do the reverse too for a kind of parameter fitting to fix our model: 1. Create a reasonable approximate model for both Kepler's expected detection bias and for planet size distribution. 2. Constrain parameter space for these models as much as possible, to minimize the search space. 3. Using these models, generate a set different planetary sets for different parameters. 4. Find the outputs with the closest match in statistical "shape" of the actually measured data. 5. generate new input parameters based on these output that lead to set outputs to refine shape until certain level of matching has been found If done naively this would probably take a lot of computation and result in large a solution space: the more parameters, the higher the conditionality of this space. So the models should be approximations with as few parameters to produce reasonable results, and with constraints on said parameter values based on known physics. This would narrow down both the parameter space to search the possibly valid outputs of this space. Based on these parameters differ from the output we had expected before, we might then get a direction of where to look for the physics that does explain the distribution.
- numbol 8y agoIf you want more, search about "inverse problem"
- vanderZwan 8y agoThanks for the tip! From the wiki page it does look like the thing I'm describing, and I guess I've encountered it many times but never interpreted it as such. [0] https://en.wikipedia.org/wiki/Inverse_problem https://en.wikipedia.org/wiki/Inverse_problem
- karol 8y agoAs a side note, the drawing attached to this article is of Edward Tufte's quality, so much information condensed into a simple-looking drawing and it's so easy to get the idea from a single glance.
- lolc 8y agoI'm actually pretty confused by that chart because the bigger planets of SOL are off the side.
- DavidSJ 8y agoThe planets detected by Kepler will tend to be unusually close to their star due to its detection method. I believe that’s why Sol looks like an outlier in that regard — it’s really that the other systems are the outliers.
- lolc 8y agoCould be. Detecting smaller planets further out is less and less likely.
- majia 8y ago> The answer was no: in more 1000 trials with randomly assigned planet sizes put through a virtual Kepler’s detection scheme, a pattern of similarly-sized planets in the same systems never emerged. This computational experiment did not reproduce what we observe in the Kepler planetary systems. Thus, the regular sizes of planets is a real astrophysical pattern. Any explanation to this? I'd assume small planets are just harder to detect. Large planets could be gas giants that react differently to our observation technique. Also they tend to form further away from the star, leading to a longer orbital period and fewer observations. Could these contribute to an observation bias and does the simulation include these factors?
- munificent 8y ago> does the simulation include these factors? Yes, that's what the "put through a virtual Kepler’s detection scheme" part refers to. So she: 1. Generated a bunch of random planet sizes. 2. Simulated what the detector would have reported for each. 3. Compared those virtual detections against the real detection data. If the two results had matched, it would imply real solar systems have random planet sizes and the bias they see is from the detector. Since the two results are different, it implies the actual solar systems are not randomly sized with the apparent uniformity coming from detector bias. (There could, of course, be a third factor where planets are randomly sized but the measured bias comes from something else.)
- Eyght 8y agoAnother possibility is intergalactic bar billiards[1] [1] https://sites.google.com/site/h2g2theguide/Index/i/540914 https://sites.google.com/site/h2g2theguide/Index/i/540914
- majia 8y ago2. Simulated what the detector would have reported for each. I think this would be really hard. For example, you need to simulate how the detector responds to different planet compositions, different signal to noise ratios at different distances from the star. A sphere in vacuum model may be a gross simplification.
- jvanderbot 8y agoSo to test for unknown bias and sensor anomalies, they put raw modelled data through the statistical machinery looking for homogenized outputs. This strikes me as wrong. If you want to know if your filter is bad, you plug in ground truth and add known noise models. If you want to know if your noise models are wrong, you cant do the same thing, you need to point your sensor at a known object (e.g. calibrate). They seemed to have done a cursory analysis of the former type, which is not the same as saying "our pea-pod hyoothesis is correct".
- dnbgfher 8y agoI don't believe this was an attempt to find bias or noise from the physical sensors, but rather was looking at the method itself. The method has some known biases that they were ensuring wouldn't explain the given pattern in the data. Depending on the depth of the simulation, it may have also been able to account for some unknown biases in the method. Now even under your interpretation, I'm curious about which known object you'd suggest they use.
- yaya69 8y agohttps://en.wikipedia.org/wiki/Axis_of_evil_(cosmology) https://en.wikipedia.org/wiki/Axis_of_evil_(cosmology)
- xen2xen1 8y agoRandom question.. If they are looking for transits, doesn't that presuppose the data will find close in planets? I believe that's not the only method, but wouldn't that push more close planets than distant ones? Would it find transits of things like Neptune or Uranus that take hundreds of years?
- lolc 8y agoCan anybody explain why the chart stops at 3 AU? All our bigger planets are off the chart.
- itronitron 8y agoSeems likely that the planets with larger orbits have not yet been detected since they will take longer to reach a point in orbit when they are transiting their respective stars. It seems premature for the paper to reach it's conclusion when Kepler has been in operation for less than ten years, but hey... publish or perish.
- irrational 8y agoSo, the Kepler method of detecting planets only works if the orbital plane (maybe not the right term) of the star we are looking at is such that the planets are between us and the star, right? So if we are looking down at the "top" of the star then no planets will obscure the star, right? Also the planets need to be passing in front of the star at precisely the right time that the planet and star and our telescope are all lined up more or less. Someone looking at our solar system would need to wait quite awhile to see Pluto pass by. If all of that is correct, how are we able to see any exoplanets? My layman's guess would be that it would be incredibly unlikely that everything would line up so that we could see anything. What am I missing in this picture?
- noselasd 8y agoThere's an awful lot of stars, it would be very unlikely that we look at all of them from the top down where we could not detect a planet passing in front of the star. Kepler glares at single piece of our galaxy and monitors about 150,000 stars simultaneously. Kepler is nice for finding large planets that orbit their stars in days. If you wanted to find planets like Pluto using the transit method, you'd have to look at its star for about 750 years (generally one wants to observe at least 3 transits) - albeit Pluto being even smaller than our own Moon, I'd guess it could not be detected.
- gmiller123456 8y agoThere are several methods of detecting exoplanets[1], the method you're referring to is the easiest and is called "transiting". Since it's the easiest, most exoplanets have been discovered with this technique. As you've guessed, it is highly unlikely for the stars and planets to align this way, and the general hypothesis as to why we've discovered so many is that there's a lot of planets out there[2]. [1] https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanet... [2] https://www.nasa.gov/home/hqnews/2013/feb/HQ_13-057_Kepler_Tiny_Planet.html https://www.nasa.gov/home/hqnews/2013/feb/HQ_13-057_Kepler_T...
- ncmncm 8y agoThis result says that random sizes and orbits are not consistent with observations. But there is a huge gap between "random" and "uniform", even ignoring all the possible different distributions. We know that our solar system is not random -- e.g., we have the "platonic solids" spacing, for our inner planets. So, our solar system is also not described by the disallowed model. It's great that some subset of random distributions are ruled out for systems that happen to have planets packed close to their star, but that says nothing at all about how we compare to the the overwhelming majority of other systems systematically excluded from the sample. As with most results that hit the popular press, any actual significance is garbled to the point of meaninglessness. But a good graphic can be worth a lot if you ignore the headline.