Most Planets In the Universe Are Homeless 219
StartsWithABang writes: We like to think of our Solar System as typical: a central star with a number of planets — some gas giants and some rocky worlds — in orbit around it. Yes, there's some variety, with binary or trinary star systems and huge variance in the masses of the central star being common ones, but from a planetary point of view, our Solar System is a rarity. Even though there are hundreds of billions of stars in our galaxy for planets to orbit, there are most likely around a quadrillion planets in our galaxy, total, with only a few trillion of them orbiting stars at most. Now that we've finally detected the first of these, we have an excellent idea that this picture is the correct one: most planets in the Universe are homeless. Now, thank your lucky star!"
so how did they form? (Score:3, Interesting)
don't planets need some kind of gravity source to pull all the dust and shit together?
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They could have formed inside of solar systems and then ejected into interplanetary space by encounters with other planets.
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Planets are a gravity source to pull all the dust and shit together. The dust and shit is a gravity source too, for that matter.
If you have enough dust to make a big enough clump, you get a star (and maybe orbiting planets, as sub-clumps). If you don't have enough, you get a planet by itself. If you have a whole fuckton-plex more, you get a galaxy. The same process happens at all scales.
Re:so how did they form? (Score:4, Funny)
this would also explain the dust bunnies that love to form under my bed
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Yes, a boatoad of these "planets" are failed stars - too little mass to start the fusion process.
We're not talking Earth-like planets here, but gas giants like Jupiter - up to the size of brown dwarf stars.
And they are likely not alone, but have their own satellites.
Then there are Oort cloud objects around stars - ice objects too small and far away from a star to form water planets like Uranus and Neptune.
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Planets are made of matter, matter is a gravity source. If that matter pulls together, but fails to ignite, you have a gas giant instead of a star. The same could happen with rocky planets. Obviously, smaller planets would take much longer to form on their own, but it could happen. And even more likely is that the planets form inside of a star system, but are ejected rather than settling into a stable orbit.
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They formed around stars and then got ejected by meteor impact, star explosion or whatever.
this is why the aliens haven't invaded yet (Score:5, Interesting)
so much resources out there for the taking, no need to come to earth
the odds (Score:2)
With a few trillion planets in orbit, makes me think that if life is a 1 in a million chance, we've got millions of planets with life just in our galaxy....with at least trillions of planets of life across the universe.
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Maybe. The core's probably a pretty unpleasant place though, with radiation levels so high i's unlikely that life could evolve. Though admittedly by the time a race masters interstellar travel it's probably well on it's way to being able to colonize the galactic core, provided they don't mind living entirely indoors.
I think you're on to something (Score:3)
Most really advance races will have probably passed through their singularity – being mechanical-beings they won't really need stars providing warmth to live by. It could be that a huge percentage of these planets are colonized by post-biological-entities and the planets around stars are left as garden areas for new post-biological-entities to emerge from.
Perhaps this is a new direction for SETI
Drake equation (Score:2)
Re:Drake equation (Score:4, Insightful)
This impacts Drake equation and might shed light as to why we have not detected any other sentient life in the universe.
No, it does not impact the Drake equation at all. The drake equation is based on R* and f(p) which are the the "rate of star formation" and the "fraction of those stars that have planets" (from your link on wikipedia). Both of these numbers are not affected by this finding.
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my mistaken(?) impression that key finding was "fraction of those stars that have planets" is lower than what we previously believed.
It's "the fraction of the planets that have stars" which does not affect "the fraction of stars that have planets" because the new thought is that there are _way_ more planets than previously estimated.
To be fair, the conversational second-person italics! style of the article is maddening to read, and far worse to skim.
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This.
The Drake equation addresses the probability of finding civilizations -- not the probability of finding planets.
As mentioned earlier, planets are not necessarily formed near stars. They can be created when enough mass coalesces to gather in one place and meet the definition of planet.
Also, some planets should be ejected from solar systems. Early solar system formations are exceedingly unstable.
As for explaining dark matter, unbound planets and proto-planets and similar partials could explain some of th
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TFS suggests that there are MORE planets than previously thought.
However, "homeless," planet is probably a very good description because planets need a source of energy to support life.
Some could have hot cores and life could exist sub-surface, but in order to be detected, we really need some life forms on the surface.
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The ratio of gas giant to terrestrial homeless planets may also be tilted more towards gas giants than terrestrial. A lot of these homeless planets may be gas giants that failed to achieve fusion and become a star.
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Homeless planets probably do fit to origin theories: 1.) Ejects and 2.) Self-formed.
Ejects would have a better chance at being smaller and denser because of the dust and debris field in the vicinity of the proto-star.
The self-formed more than likely are giants.
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Gas giants could have moons that receive heat from gravitational changes and radiation from the gas giant. These moons might have life on them. It's an outside chance, yes, but given how many planets there are out there, I'd say the chances of one of these being in this situation is probably high.
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There's also the possibility of dense star formation, or other sources of intense radiation with nearby rouge planets.
A dense stellar nursery will have lots of interstellar dust, (and a shitload of local radiation), and will also have a good chance of producing such rouge planets, because of the presence of the large interstellar cloud, and the perturbations caused by the protostars.
It takes time for these dense star forming regions to push each other apart from radiative pressures, and without a local star
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If you have less planets that previously assumed, it follows that there would be less planets that contain civilizations, and less civilizations.
Fewer. Not less.
And no, it doesn't follow. Having a million times as many gas giants won't increase the chance of civilizations noticeably. And in this case, we're talking mostly super-Jupiters, consisting almost entirely of hydrogen and helium.
What Drake's equation counts isn't planets, but "the average number of planets that can potentially support life".
Life as we understand it can't exist in a ball of gas and liquid hydrogen and helium. We cannot rule out that such life exists, but it would be an ex
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This impacts Drake equation and might shed light as to why we have not detected any other sentient life in the universe.
No, it does not impact the Drake equation at all. The drake equation is based on R* and f(p) which are the the "rate of star formation" and the "fraction of those stars that have planets" (from your link on wikipedia). Both of these numbers are not affected by this finding.
Really it doesn't matter much since proposed numbers for the various factors vary so wildly, but it could change the Drake equation if you wanted (there are other factors listed on the Wikipedia page that could change it as well). In this case, the first three multipliers, R* x fp x ne, estimate the rate at which habitable planets form, but since those terms focus entirely on planets around stars, it ignores habitable homeless planets. So you might replace that with (R* x fp x ne + Rh x fhh), where Rh = r
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"This impacts Drake equation"
If planets are not orbitting a star, its unlikely they would evolve life (as we know it, Jim) much less a technical civilisation
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Exactly. Biological life seems to need a certain amount of warmth; a rogue planet, which doesn't receive any heat from a parent star, is going to have a very cold surface, even if the interior is warm. Life as we know it wouldn't probably evolve on such a planet; it'd just be an ice world.
So this finding is interesting, but I don't see how it would affect the Drake Equation. If we want to find life that resembles us, we're probably only going to find it in star systems, on rocky planets within the star's
Re: Drake equation (Score:2)
Re: Drake equation (Score:2)
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They'd have to really dislike us to put out a contract on us at interstellar distances....
On the other hand, we might get a ticket for littering by and by, if Voyager ever wanders near an interstellar traffic cop.
Homeless...and smell like urine? (Score:2)
>> most planets in the Universe are homeless
I wonder if they also smell like urine (http://science.slashdot.org/story/14/10/26/1226209/rosetta-probe-reveals-what-a-comet-smells-like).
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Sorry, I gave my last yottaton cloud of hydrogen gas at the office.
Does not follow (Score:2)
Just because most planets belong to a solar system doesn't mean that most solar systems don't have planets. That it is atypical for a planet to orbit a star in no way indicates that it is atypical for a star to have orbiting planets.
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You're reading that wrong.
So, there are "around a quadrillion" planets, and only "a few trillion" of them orbit stars.
So, there's 10x, or 100x, or even 100x as many planets which, DO NOT b
Great.... (Score:3, Funny)
Very odd... (Score:2)
you'd think most of them were captured in larger gravity wells rather then wizzing around.
Re:Very odd... (Score:5, Informative)
As I understand it, getting "captured in a gravity well" is actually pretty tricky. Unless you form in orbit around a larger body, you're most likely by far to just do a hyperbolic single-pass encounter. To be captured, you need to impact the larger body (a very rare occurrence), or dissipate your momentum in its atmosphere (almost as rare), or have some sort of multi-body interaction (probably rarer still).
This is all approximate -- technically, I guess everything orbits everything within its historical light-cone. Almost none of those orbits are anything close to periodic, though.
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Actually, I suspect multi-body interaction would be the most common form of capture, far more common than impact (aerobraking included). Impacting a planet requires hitting a pinprick in a football field almost dead center, there are many orders of magnitude more paths that will result in a near miss and gravitational slingshot, half of which will rob you of angular momentum. You'd likely need to hit several such "losing" planetary slingshots in a row before being captured by the sun, but the odds would s
Classification (Score:5, Funny)
Actually these are not planets according to the new classification.
First, it must orbit the Sun.
Second, it must be big enough for gravity to squash it into a round ball.
And third, it must have cleared other objects out of the way in its orbital neighborhood.
http://missionscience.nasa.gov... [nasa.gov]
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By that definition, there's only 8 planets in the entire Universe. They may need to update their definition of planet, especially the first point.
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It means to be a planet it at least needs to be orbiting a star. So these are rogue planets.
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It's pretty clear in the definition that "Sun" is a proper noun denoting, specifically, the star that we orbit.
Re:Classification (Score:4, Informative)
There are "planets". 8 of them.
Then, there are a bunch of "dwarf planets" - Pluto, Ceres, Eris, etc.
"Minor planets" - there are thousands, millions, I'm not sure, but a lot of these.
"Exoplanets", let's divide these into two categories - system exoplanets, that orbit a star like our planets, dwarf planets, and minor planets, and systemless exoplanets that do not orbit a star.
These are all different kinds of planet. In astronomical terminology, the word "planet" by itself is reserved for the Big Eight, but all these other things are a kind of planet.
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Actually these are not planets according to the new classification.
The IAU classification only applies to bodies within this Solar System. It does not apply to bodies outside the solar system.
RESOLUTION 5A
The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A "planet" [1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) sha
Science Fiction got it right again (Score:3)
Space 1999 was so prescient!
Two points (Score:3, Funny)
2) These should be called slacker stars. They had so much potential, but just blew it all and eventually their parent's kicked them out.
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Actually, sounds like most of them probably never had parents to begin with - they created themselves with no help from anyone, and just couldn't finish the job because the first planets to the party had already gobbled most the gas for themselves to become stars, and then proceeded to scatter the remaining gas to make the job even *more* difficult for the latecomers.
Maybe we should call these planets the galactic 99.9%.
Planetary System Without A Star? (Score:3)
Planetary System Without A Star? (Score:4, Informative)
We've seen that with Jupiter, if it were not for being in orbit around Sol, Jupiter and its moons would effectively be their own dark solar system.
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It depends upon how stable orbiting systems are formed. There has to be a transfer of angular momentum. That angular momentum is probably transferred via magnetic fields. The magnetic field needs something to interact with, such as ionized particles. Ionizing particles requires an energy source, such as a hot central body. For Jupiter and it's moons, that could very well be the Sun.
(Note: it has been a while since I studied this stuff, so I may be a bit off. But the most important point is that it is
weird phrasing (Score:2)
I'm sure those planets would prefer to be thought of as "free".
Hmmmm .... (Score:2)
I will naively assume planets generally form around stars during stellar formation, and don't just spontaneously show up.
So, the homeless planets either spun out during formation ... or ... what, are subsequently ripped away by some other phenomenon? Possibly passing gravity? That about right?
So, if they're hard to see because they don't emit light ... can they possibly be part of the whole dark matter thing? Or is that one different?
If there's quadrillions of planets, and trillions orbiting stars ... th
Interesting (Score:2)
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dark matter? (Score:2)
Sheesh. So is this the simple explanation to "dark matter" problems in cosmology?
This makes sense (Score:5, Interesting)
Systems composed of multiple stars (binaries, etc.) are more common than singular stars, like our Sun. A binary system is a risky place to be -- there is a strong probability that the gravitational interaction between the paired stars would, given enough time, eject any planetary body which forms there -- the "stable" regions depend on the orbital parameters of the two (or more) stars and can be limited to very narrow bands. So, if planetary formation is a typical process around stars and binaries are more common, then it's likely that the galaxy has a large population of planets ejected from unstable orbits around binaries.
For what it's worth, conjecture is that the Sun formed in a cluster and was, itself, ejected. Nearby stars with identical spectra (implying they formed from the same source material) have been identified.
Homeless planets (Score:3)
It's true, just saw one on the corner. Had a cardboard sign, "Will orbit for $$$".
not a particularly good article (Score:2)
But here’s the funny thing: when we work out the numbers of our best theoretical calculations, the ones produced by getting kicked out of young solar systems represent far less than half of the rogue planets that we expect.
So the author tries to explain a huge number of expected rogue planets, but fails to describe how we've arrived at the number in the first place. "Work out the numbers"? Yes? Could you please share? Why didn't you start with that in the first paragraph?
Also what's with all the exclamation marks? Is this article pitched at grade-schoolers? Fine but if so, what is it doing here?
Re: Not Planets (Score:5, Interesting)
Planet is Greek for wanderer. So, I think the name is even more appropriate.
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Any body that is sufficiently massive enough to pull itself into a reasonable facimile of a sphere, yet not massive enough to generate energy from fusion, is a planet, whether it orbits a star or not. And there's your missing "dark matter".
Tell that to Pluto.
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The IAU definition only applies to objects in this solar system. It says nothing about objects outside this solar system. It is very clear about that.
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The IAU definition only applies to objects in this solar system. It says nothing about objects outside this solar system. It is very clear about that.
So obviously there are no "planets" at all outside our solar system. ;-)
Maybe astronomers should just make up a new term for the concept. Or maybe several terms. After all, how useful is a term that includes both Mercury and Jupiter? Especially if it excludes Pluto, Titan and Sedna.
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Well, in the absence of an explicit definition wouldn't you be presumed to fall back on the default of "things gravitationally bound to the sun"? In fact, in what way could an object not bound to the sun be considered part of the system? Even a rogue planet passing through would only be a temporary anomaly, not an enduring part of the system.
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To me there will only ever be one rouge planet. Maybe I'll get to set foot on it.
One day, dear Mars, unless I die first.
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I'm sure what this article is calling a Planet meets these 3 criteria b
TopSlot (Score:5, Insightful)
I always wondered why wandering planets couldn't be used instead of dark matter to explain where all the missing mass is.
Re:TopSlot (Score:5, Informative)
Not a physicist, but there's a few reasons. First and foremost, I believe there simply aren't enough wandering planets to explain it. Dark matter accounts for something like 90% of the gravitational effects that we see. If wandering planets were to blame for that much mass, they would definitely be much, much more noticeable even without giving off light like stars. Secondly, wandering planets simply don't fit the bill for what we're seeing in regards to gravity - if it were all planets, we would be seeing much different galactic formations.
Re:TopSlot (Score:5, Funny)
This is the most insightful and informative ever to follow from the word "penis".
Re:TopSlot (Score:5, Funny)
And of course, I accidentally a word.
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Re:TopSlot (Score:4, Funny)
Don't get cocky!
Flawed model? (Score:5, Insightful)
Dark matter accounts for something like 90% of the gravitational effects that we see.
I've always suspected that "dark matter" very likely isn't matter at all. I suspect it is simply a gap in our model similar to how relativity filled in gaps for Newtonian mechanics. Dark matter (and dark energy) are basically placeholders for observations that do not match our model. That means one of two things. Either there is something we haven't observed yet OR there is something missing from our model. Both are quite possible but we seem fixated on that former when it could very easily be the later.
I actually do have some background in physics (college minor and worked in some research labs) and I've never have any "real" physicist give me a satisfactory explanation as to why invoking some mysterious matter/energy is a more likely answer than a gap in our models. We understand gravity probably the least of the four forces and we don't have a model that integrates it into our Standard Model. Seems to me that the place to look may very well be in the math rather than in the stars.
Re:Flawed model? (Score:5, Insightful)
A lot of physicists, including Neil deGrasse Tyson, have said that "Dark Matter" is actually a pretty poor name for the phenomenon because it's almost certainly not just some exotic form of matter, but something else entirely that's at work. However, like many things in science, the early name was catchy enough to stick in spite of being a crappy descriptor.
Re:Flawed model? (Score:4, Interesting)
A lot of physicists, including Neil deGrasse Tyson, have said that "Dark Matter" is actually a pretty poor name for the phenomenon because it's almost certainly not just some exotic form of matter
Unfortunately a lot more physicists talk about dark matter (in public anyway) as if it is actually matter of some sort despite the fact that we have no actual direct evidence that such a thing actually exists. Now maybe dark matter really does exist but all we have right now are some observations that don't match our models. Could be that our powers of observation are simply too limited in some way right now OR it could just as easily mean we have a flawed math model. I tend to think the latter is significantly more likely but obviously cannot rule out the former.
Physicists and scientists in general though are pretty bad at explaining concepts to the general public. I'm more educated than most people are with regard to physics and I have yet to find an explanation of the Standard Model that is even vaguely approachable to a layman such as myself. They also are pretty bad at communicating where the lines between what we know and what we do not know actually are.
Flawed Understanding (Score:3)
A lot of physicists, including Neil deGrasse Tyson, have said that "Dark Matter" is actually a pretty poor name for the phenomenon because it's almost certainly not just some exotic form of matter
No clue who this Tyson guy is but either he, or you, have confused Dark Energy with Dark Matter. Physics is not determined by majority vote but I very strongly suspect that the numbers will come down massively in favour of Dark Matter being an exotic form of matter by which I mean some as yet undiscovered particle. Dark Matter is a very appropriate name for it since it almost certainly is matter and, lacking any electrical charge, will not interact with light at any wavelength. Attempts to explain Dark Mat
Show me the evidence (Score:3)
No clue who this Tyson guy is but either he, or you, have confused Dark Energy with Dark Matter.
Then you should spend 20 seconds on Wikipedia before making an idiot of yourself in public by not knowing who one of the most famous astrophyscists in the world is. Here's a clue - watch the series Cosmos: A Spacetime Odyssey [wikipedia.org]. He certainly isn't confused about the difference between dark matter and dark energy and I'm pretty certain I'm not confused either.
Physics is not determined by majority vote...
I don't recall anyone claiming that it was.
...but I very strongly suspect that the numbers will come down massively in favour of Dark Matter being an exotic form of matter by which I mean some as yet undiscovered particle.
Based on what evidence? You might be right and it may very well be exotic matter but like you said it isn'
Re:Flawed model? (Score:4, Interesting)
As an example that worked out -- the neutrino was originally proposed as an unobserved, mysterious matter particle to avoid having to modify the laws of conservation of momentum and energy when applied to nuclear beta decays.
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As an example that worked out -- the neutrino was originally proposed as an unobserved, mysterious matter particle to avoid having to modify the laws of conservation of momentum and energy when applied to nuclear beta decays.
All I'm saying is that "dark matter" may or may not turn out to be matter at all. Nobody really seems to know at all. We have some observations that don't fit our models. That is good because it gives us something to look for. What's bad is that we are invoking some mysterious exotic "matter" with no actual model to explain what we are seeing. We should simply be saying it is a mystery rather than saying there "must be matter we cannot see". Maybe there is but that's not the only possible explanation.
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FTA:
But if you do the math, that means for every star-orbiting planet like ours in the galaxy, there may be up to 100,000 planets that not only don’t orbit one now, but most likely never did.
The sun is around 330,000 times more massive than the Earth. Thus those 100,000 other Earths out there have a mass of 1/3 our sun. But, there are of course several other planets in our solar system. So the mass of all those rogue planets (100,000 : 1 ratio of rogue planets to planets in the solar system) would be several times greater than the sun. Not exactly a trivial amount of mass there. That could explain a big part of dark matter, but of course people a lot smarter than me have already consid
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Several times the size of our sun is stil a VERY long way from being enough matter to explain what "Dark Matter" is meant to explain.
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And I always wondered why people post their idle ponderings as a reply to anonymous cowards posting their penis. Where is the connection here? I mean it happens all the time here, entire endless discussions always seem to trace back to a first post racial slur and playground profanity.
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It was the first reply and no one had posted any reply to it. The default comment sorting system means that I get maximal exposure by replying to it.
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To hell with karma, when I pull a stunt like that I'm looking to get some interesting replies.
Re:TopSlot (Score:5, Informative)
http://en.wikipedia.org/wiki/M... [wikipedia.org]
http://en.wikipedia.org/wiki/W... [wikipedia.org]
Re:TopSlot (Score:4, Funny)
So what you're saying is that I'm a ... MACHO man? Maybe even a macho MACHO man?
Also, interesting reads.
They've only found one! BAH! (Score:3)
How can they claim that there's more of these homeless planets than not when they've only found one of them...ever!
I understand that we don't have to see something for it to be there but, this leap is just too big to bear.
Re:Dark Matter (Score:5, Interesting)
(FYI)
There are a few reasons astrophysicists know that it is extremely unlikely that dark matter is baryonic. First of all if all the stars in a galaxy shine on an object it heats up, this heat causes the release of radiation, called thermal radiation, and every (baryonic) object above zero kelvin (or -273.14 deg celcius) emits this radiation. However, dark matter does not emit any radiation at all (hence the name dark!)
If dark matter were baryonic it would also mean that it could become light emitting. If we got a clump of baryonic matter* and put it in space it would gravitationally contract, and would eventually form a star or black hole** - both of which we would be able to see.
So, because of these reasons the dark matter in galaxies and in galaxy groups/clusters cannot be baryonic, and so cannot be planets, dead stars, asteroids, etc. It would definetely not be planets as there is no way 10-100 times the mass of the stars in a galaxy would be planets, as the mechanism for making planets relies on supernovae, and the number of supernovae needed for the that many planets would be far too high to match our observations. I hope that this answered your question!
*provided the clump of baryonic matter was large, and the amount there is in galaxies definitely is!
** we don't observe black holes directly, but can see radiation from their accretion disks.
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Pretty thin considering the article talks about observed planets exceeded one expected number of planets model and also discusses *other sources* of planets...
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If you're going to copy an answer from a post on another website, at least give the link:
http://astronomy.stackexchange... [stackexchange.com]
And that answer obviously is wrong. If matter has clumped together into planets, it obviously hasn't clumped together into stars or black holes, and instead has clumped together into objects that are very hard to detect.
Arguments against dark matter being rogue planets are generally based on lack of enough microlensing observations and expected size distributions. But those are far from
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Clearly the median planets per star for stars with at least 1 planet is a lot higher than the "avg" per all stars.... lies damn lies and statistics.
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but we are already using "galaxy" to describe that, which is a pretty cool word.
It may sound cool to us English speakers, but it really just means "milky" in Greek.
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My new tax bill will completely eliminate planetary homelessness by creating an intergalactic market opportunity providing dwarf stars to the most poverty-stricken of planets at a viable profit.
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What's really annoying is that English punctuation doesn't give any indication that a sentence should be read in an exclamatory or querying tone until you've already finished. It's one of the few things I prefer about Spanish.