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Solar Systems Like Ours Are Likely To Be Rare
KentuckyFC writes "Astronomers have discovered some 250 planetary systems beyond our own, many of them with curious properties. In particular, our theories of planet formation are challenged by 'hot Jupiters,' gas giants that orbit close to their parent stars. Current thinking is that gas giants can only form far away from stars because gas and dust simply gets blown away from the inner regions. Now astronomers have used computer simulations of the way planetary systems form to understand what is going on (abstract). It looks as if gas giants often form a long way from stars and then migrate inwards. That has implications for us: a migrating gas giant sweeps away all in its path, including rocky planets in the habitable zone. And that means that solar systems like ours are likely to be rare."
Get Bruce Willis on the phone, time to go "Armageddon" on Jupiter's ass.
Sig? SIG? We don't need no stinkin' sig!!!
I didn't RTFA, but I will when I get home.
But on the surface it seems more to me that they're just saying that solar systems have a life cycle that is marked by the location of gas giants. I don't really think that means that our setup is rare.
But if I am misinterpreting the blurb and that is what they're proposing I would still say we need to hold our horses on any real judgement. We've found these solar systems because our current method of seeking these solar systems out is going to be more likely to find this kind of activity as opposed to what we have here at home. I think we're jumping the gun a bit on this one. I say let them work it out for a couple of more decades and even then we should be a bit more cautious about such sweeping statements.
Dedicated Cthulhu Cultist since 4523 BC.
when they have capability of detecting Earth > Venus > Mars size planets
they don't have much data do they to base their theory on?
If gas and dust get blown away, what's to say that rocky planets weren't originally gas giants? It could be that the gases were (mostly) stripped away, leaving the core. Perhaps our rocky planets formed further out, migrated in, but found steady orbits as they lost mass.
What if I do the same thing, and I do get different results?
I thought it was commonly understood that for a solar system like ours to exist, that there needs to be a gas giant to act as a "protector" for the habitable planet(s). That is, the larger planet acts as a gravity well to lure some of the larger objects that could collide into the habitable planet. From the summary, it merely seems to be saying that the gas giant forms closer to the star than originally thought, but that it migrates outwards later in its life and helps to clear a zone for the habitable planet to exist.
I know there are many solar systems with inhabitable planets in the galaxy and others, I know it!
I've seen the documentary on TV!
What was it called... hmm Stargate, yes, that's it!
And the Ancients seeded life over all of them, they said so in Stargate Atlantis!
I suppose they didn't watch TV enough to have missed such a proof.
I can't follow 100% the article, so hopefully someone can clarify this point of curiosity for me.
Is one of the implications that solar systems could at one point be similar to ours? Gas giants far away with smaller planets towards the sun? And then the gas giants slowly creep towards the sun, wiping out the smaller planets that get in the way?
... or should I start welcoming our Jovian overlords?
"... Everything looks like a nail" situation to me. We've only really had the ability to discover LARGE planets around solar systems. Also, the shorter the orbit period, the easier it is to detect.
So logically, the planets we've found to date look NOTHING like those of our solar system. Jupiter's orbital period is 4332.71 days!!! And we are comparing that to the VAST majority of discovered planets(hot Jupiters) with orbital periods of less than 10 days?
Seems like this article belongs in the "Are US Voters Informed Enough About Science?" thread if you ask me.
Prof. Farnsworth - "Oh a lesson in not changing history from Mr I'm-My-Own-Grandpa!"
Even if solar systems configured like ours are rare, it doesn't suggest that is a problem for either the development of life or intelligence as we'd recognize it (and really is no problem for any other forms of "life").
A gas giant in the "habitable" zone may have multiple moons that end up habitable. If Jupiter was in Earth's orbit its entirely possible 2-3 or more of its moons would be habitable in some form.
That both increases the odds by having more places habitable, but increases the possibility of panspermia, so you could actually have greater diversity in that situation.
Actual data is highly biased towards gas giants in close orbits because that's what's easy to detect.
Simulations like these don't have sufficient real-world data to make any reasonable statements about what kinds of solar systems are likely.
Also, "rare" is a relative term; if 1% of all planetary systems contain a habitable planet, there would be a lot of them and they'd be rather closely spaced.
Nothing says "sanity" like a preemptive defense.
Are you suggesting that Jupiters migrate?
--
Incoming!
The Electric Universe theory contradicts Time Cube theory, and thus cannot be valid, as Time Cube theory encompasses everything.
Really, in terms of the universe, EVERYTHING is rare. Galaxies are rare. Stars are rare. Matter is rare. About the only thing that isn't rare is space itself. Draw a line segment across the universe, make it trillions of miles long. How many atoms did you actually touch with that line?
ADVENTURERS! - ANTIHERO FOR HIRE - CARDMASTER CONFLICT
From Douglas Adams:
I mean this is a great world, it's fantastic. But our early man has a moment to reflect and he thinks to himself, 'well, this is an interesting world that I find myself in' and then he asks himself a very treacherous question, a question which is totally meaningless and fallacious, but only comes about because of the nature of the sort of person he is, the sort of person he has evolved into and the sort of person who has thrived because he thinks this particular way. Man the maker looks at his world and says 'So who made this then?' Who made this? - you can see why it's a treacherous question. Early man thinks, 'Well, because there's only one sort of being I know about who makes things, whoever made all this must therefore be a much bigger, much more powerful and necessarily invisible, one of me and because I tend to be the strong one who does all the stuff, he's probably male'. And so we have the idea of a god. Then, because when we make things we do it with the intention of doing something with them, early man asks himself , 'If he made it, what did he make it for?' Now the real trap springs, because early man is thinking, 'This world fits me very well. Here are all these things that support me and feed me and look after me; yes, this world fits me nicely' and he reaches the inescapable conclusion that whoever made it, made it for him.
This is rather as if you imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in - an interesting hole I find myself in - fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!' This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it's still frantically hanging on to the notion that everything's going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.
This is a big deal, because back when we only knew about our solar system, we formed theories to explain it. These theories imply that we wouldn't find many cases of large gas giants near suns. The current observations falsify these theories. We don't have to have a total picture of every planet in the vicinity to know that; detecting too many large planets is sufficient.
Your issue of our ability to detect only these types of planets is totally irrelevant to the main point about our theories making now-falsified predictions... which makes your accusation that others are misinformed about science that much more ironic. Perhaps you should be sure your ducks are in a row before accusing others of not understanding science.
The interesting data is not how many hot Jupiters are found, but how many stars do not have hot Jupiters.
Here's a list of extrasolar planets (last updated in January); and another list. Note the large number of stars that have planets found with mass less than Mj. The converse of that is that those stars do not have planets of mass greater than Mj. The problem, of course, is that negative results are much less published than positive results. However, here is a list of three published papers that listed stars with no planets found (that is, no planets large enough to detect-- which is to say, no hot Jupiters. This list is somewhat out of date, as of 2006.)
So the story is a little incomplete. Some solar systems have hot Jupiters, which in their migration inward disrupt smaller, earthlink planets... but by no means all.
http://www.geoffreylandis.com
Best estimates put us at 30 billion planetary systems in the Milky Way galaxy alone. If only 0.0001% of those planetary systems holds an Earth-like planet capable of sustaining life, that's 3 million Earths, just in the Milky Way. Now consider that figure holds for all galaxies. A conservative estimate from Nasa's scientists puts the universe at 125 billion galaxies. That's 3 trillion 750 billion planetary systems. If only 0.0001% of those systems are host to life-sustaining Earth-like worlds, that's 375 billion Earths in the universe. Perhaps that is rare, considering how stupidly big our universe is... but that is still a hell of a lot of Earths.
These ideas aren't _directly_ coming from the admittedly biased detection of large gas giants with close in orbits. Everyone knows that the detection scheme we use is biased to find them, and it would be impossible to find many systems like ours using it. But that doesn't really matter at all. The very fact that Hot Jupiters exist at all, have big implications to how systems form.
Finding these big planets close in meant that old planetary formation theories had to be revised. New theories, based off how these planets could form at all, state that planets don't form in place - they form farther out and migrate in. It also means the Solar System is lucky Jupiter stopped where it did - if it migrated further inwards all the planets in the inner solar system would've been flung into space...
It seems like every other day there's a new article/paper/prognostication conclusively demonstrating the rarity/abundance of Earth-like planets/systems. Honestly, at this point I'm just going to hold my judgment until I can get out there and see for myself.
Outsider theories always have the burden of proof on their own shoulders. To paraphrase someone famous, "there are many questions fools can ask that wise men struggle to answer." There's no where this applies more than in science. Creation Science can throw out some sticky questions and make some points that are hard to disprove.
But Science is about proving things, not suggesting every possible idea and disproving them one by one. For a well established idea that has made a lot of successful predictions, even a known incomplete idea like the standard cosmological model, to be tossed aside, there needs to be an overwhelming amount of evidence, not just some compelling questions.
If an alternative model of the universe explains the preponderance of evidence we already have (such as the background radiation, the count of galaxies, the scarcity of structures above a certain scale, the calculated mass of galaxies, the total amount of gamma radiation etc.) as well as a current theory, as well as making successful new predictions that existing models failed to make, then over a process of several years, people in the field would become convinced, and as the literature is peer reviewed, the dogma would shift. But established scientific ideas are SUPPOSED to be dogma. It isn't politics. Equal time isn't given to competing ideas, that's not the way it works. There are too many bad scientists and professional crackpots, the system would collapse without a hierarchy of opinion.
And all science works this way and always has. Even the sciences that cure disease and deliver technological miracles. Since those things keep happening, I'm confident as a semi lay person that science, while certainly getting many small details wrong and making mistakes and sometimes taking too long to come to the right conclusions, is still heading in a monotonically positive direction.
In Capitalist America, bank robs you!
Yes, our theories were WAY off. No one predicted that these hot Jupiters were out there. Now they make up almost all of the planets we've detected to date. The point I was trying to make is that we can't detect solar systems like ours yet. Unless MAYBE it was in the alpha centaurus system and then MAYBE if it's Jupiter equivalent were to pass in front of one of the stars.
Please, tell me how many exosolar planets we've found with orbital periods greater than 365 days? How about 4000+ days like Jupiter?
Talking about how rare we are, without even another example, because we lack the ability, is just another theory that will fall - kinda like the planet formation theories that lacked the ability to predict "hot Jupiters". Now they have gone to the other extreme and theorized that EVERY solar system starts out with hot Jupiters. You know, because that is all we can presently detect.
How is that irrelevant? It's EXACTLY the "To a hammer, all looks like a nail" analogy I started with. Since that is all we have the ability to find at present, now all solar systems must start out that way?!?!?!?
This is the same mistake all the theorists made to start with, since all we had was our own solar system to base this upon. Now they have gone exactly the opposite way in their theories which is repeating the same mistake they initially made.
Yes, you adapt your theories based upon more and more observational data. But when you KNOW your observational data is limited to one subset of possible outcomes(which makes our own solar system damn near impossible to form) and you claim "victory", that's just very illogical to me.
Prof. Farnsworth - "Oh a lesson in not changing history from Mr I'm-My-Own-Grandpa!"
But Science is about proving things, not suggesting every possible idea and disproving them one by one.
Where on Earth did you get that idea? One of the first things you learn about science is that it doesn't prove anything, only disprove. The scientific method is a three step process:
You observe phenomenon, create a theory that explains it and makes some predictions and then test these predictions. If the observations don't match the predictions you either discard or refine the theory. If they do, then you keep it around until you find some new observations that don't match up with the predictions.
The reason creationism is not science is that it makes no testable predictions. Whether it is true or not can not be tested and so is an irrelevant question to science.
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(From the Galileo Wiki) http://en.wikipedia.org/wiki/Galileo_probe#Galileo.27s_atmospheric_entry_probe
"The 339 kilogram atmospheric probe, built by Hughes Aircraft Company at its El Segundo, California plant, measured about 1.3 meters across. Inside the heat shield, the scientific instruments were protected from ferocious heat during entry. The probe had to withstand extreme heat and pressure on its high speed journey at 47.8 km/s.
The probe was released from the main spacecraft in July 1995, five months before reaching Jupiter, and entered Jupiter's atmosphere with no braking beforehand. It was slowed from the probe's arrival speed of about 47 kilometers per second to subsonic speed in less than 2 minutes."
Do you know why they though solar systems like ours would be common? Computer simulations of solar system formation. In fact, the "standard model" was even published in Creative Computing, back in the day...
What were these models based on? The only example of a solar system we knew; our own. "Of course" there will be rocky planets near the sun and gas giants further out, it only makes sense.
So then we get better telescopes that can detect Jupiter-sized planets, and they show us lots of systems with gas giants in close. The model, based on a single example, is wrong. So we re-jigger the model to match the new observations, and conclude THAT one must be right.
$50 says once the interferometric planet finders come online this model goes into the trash heap as well. The universe clearly doesn't give a crap about our models, and builds whatever it wants.
Maury
> The energy from this decay melted the early earth.
No it didn't. Gravitiopotential from infalling rocks did.
> Look up the term "iron catastrophe" for more information.
Yes, please do so...
http://en.wikipedia.org/wiki/Iron_catastrophe
Maury
Science is about proving things, not suggesting every possible idea and disproving them one by one.
Exactly the opposite is true. Science is never about proving anything. Mill's "black swan" analogy illustrates how we can make reasonable inferences and still be wrong because nature is otherwise. Every swan you've ever seen is white, so you think "all swans are white, and certainly none are black!" Upon discovering that some swans are black, the rule is not so fast. It might be tempting to claim that no swans are plaid, but even this is not provable. Nature could turn out to be different than it appears.
Creation Science can throw out some sticky questions and make some points that are hard to disprove.
They cannot be disproven, even in principle, and this is the last bastion of special creationists; they know nobody can prove so much as "the world wasn't created 5 minutes ago, with all its state and photons in flight and past memories in place", and they prey on people who think this is a failure of science. Doing science is about making wise inferences, and claiming special creation is not wise inference because empirical evidence detracts from (but does not *disprove*!) it.
established scientific ideas are SUPPOSED to be dogma.
No, scientific ideas are supposed to be meritorious.
It isn't politics. Equal time isn't given to competing ideas, that's not the way it works.
What you mean to say is that science isn't democratic. This is a result of its being a meritocracy and not a feel-good daycare where every idea gets a shot no matter how unmeritorious it may be. The following statement is a corollary:
the system would collapse without a hierarchy of opinion.
Quite right. The hierarchy of which you speak arises because not all ideas have equal merit; that is to say, not all ideas are equally scientific.
Hmm. Every time our knowledge of the universe expands, there is always a group of scientists who rush to say that the new evidence indicates that we are, in one way or another, the center of the universe. And when that conclusion is invalidated by still more new evidence, they go hunting for another reason to reinstate their conclusion. The "Rare Earth" faction is just the latest iteration of the same deep-seated emotional bias that gave us geocentrism.
We have exactly one stellar system that we have studied in detail and exactly one example of a living ecosystem, and all our knowledge of other stellar systems comes from techniques that exclusively detect stellar systems with a massive planet in a tight orbit around its star. It seems to me that our sample size is too small to reach any conclusions at all, and until we have better tools for observing other stellar systems in high detail, discussions about what constitutes a "normal" stellar system barely rise above the level of pure speculation.
Proud member of the Weirdo-American community.
The most important thing that you need to understand is that the large number of "hot jupiters" that have been found have essentially disproven existing theories of solar system formation. This is not a case where a new theory is proposed to replace an existing theory that already explains most of the evidence ala Einsteinian physics replacing Newtonian physics. This is a case where we have essentially no theory at all that explains the observed evidence.
The cake is a pie
Doesn't seem to work out for me. Their logic is that star systems have a timeline related to gas giants, so star systems like ours are rare? I guess the problem here is the totally subjective word "rare" But I don't see how star systems nearly the same age as ours (far gas giants) can't be just as common as star systems that are older (near gas giants) So rare? probably, but same way you could say "people who live with their parents are rare, because when people get older they generally move out of their parents house" (and we're talking all people, not just adults)
Not all life is cyber. Extra Income
But space, the planets and galaxy are too numerous to imagine. Basically infinite.
Rare x Infinite = Infinite
They might be thousands of lights years apart, but there are still billions of them.
This is one of two truly insightful comments in the entire thread. The other post is about how gas giants that wander towards the star might have their gasses blown away by the star over time, and leave only the core.
Just because the configuration of a star system isn't exactly like ours, doesn't mean it can't support life. Our gas giants have a multitude of moons, many of whom are very close to Earth in composition. And it's not like gas giants suddenly up and leave their moons behind when they head towards the sun. If any of them wandered closer to the sun, I'll bet some of those moons will have a high probability of life.
Furthermore, the smaller rocky planets in the center certainly have a chance of becoming the moon of a gas giant as it passes by. Granted, any existing complex life on those planets might be wiped out by the change, but that doesn't mean new complex life wouldn't arise afterwards once the gas giant settles into a stable orbit.
The conclusion that our type of system is rare is probably valid based on the new models. But the conclusion that intelligent life is equally as rare is probably invalid.
"If a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be."
Personally I think it's hard to decide if our planetary system is rare or not just by computer simulations. There are too many factors involved to make it easy to calculate how a planetary system evolves.
There have been many guesses over the last century about how the planets did form. But from the data we now have from a few other planetary systems we can at least say that a few of them have large planets (gas or not remains to be seen).
And what would say that a planet has to be the size of earth to provide for life? A gas giant may be good for life too, but maybe not the life we know here.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
You and colmore are both right. Colmore beautifuly summarized how science actually operates. Your observations reflect understandings gleaned from the philosophy of science, in particular Karl Popper's falsifiability criteria. Popper developed this idea to show how one can delineate science from pseudo-science. It is a valuable philosophical insight and is useful as a criteria of demarcation between science and unscientific ideas. But, it is not a good foundation for understanding the actual methodologies used by science. Actual science proceeds based on some assumptions such as the uniformity of natural causes that cannot be proven, but which underlay belief in the validity of probabilistic induction and the idea that science illuminates "truth" in some sense and gives us greater knowledge of reality.
here's a good chance that one or more of the inner planets is in trouble before the Sun goes nova.
A nova is caused when a white dwarf star accrets a significant amount of mass from a neighboring body. Our Sun will end up as a white dwarf, but without a companion of any significant size, it is high unlikely that it will ever go nova.
It's also not massive enough to go supernova. So basically, the Sun is simply not likely to ever explode in any way. Eventually it'll swell into a red giant and after that it'll mostly start to slowly dissolve it's outer layers. It'll go out with more of a fizzle than a bang.
That said, when the Sun swells into a red giant the inner planets are effectively screwed. Mercury, Venus, and quite likely Earth will be engulfed within the Sun.
"People who think they know everything are very annoying to those of us who do."-Mark Twain
Our knowledge is nowhere near thorough enough to make a call like that. We've identified 250 planetary systems, all closer than 100 light years, and we haven't even begun to image terrestrial-type planets yet. Saying this would be like saying all the beaches of the Earth are composed of igneous black sand on the basis of the black sand beach in Hawaii. We still only have a couple of pieces, it's a bit premature to say what the puzzle is a picture of.
"I disapprove of what you say, but I will defend to the death your right to say it." - Evelyn Beatrice Hall, re Voltaire
Cassini-Huygens is orbiting Saturn right now. New Horizons said hi to it last month when it passed Saturn orbit. It's now on its way towards Pluto. But then, it's still just following in the footsteps of its brother Voyager 2, which visited all four gas giants in our solar system and is now putting around in interstellar space.
So the answer to your question is no.
It wasn't 20 years ago when we hadn't detected another planet yet and we didn't know if planets formed around other stars. Now we know they are common, but the ones we detect are large and close to the sun. There's a reason for this: the method we use to detect extrasolar planets works by detecting the gravitational tug between the planet and star by the changing of the star's luminosity over time. If there's a 72 hour cycle where the star dims and brightens, then we know there is a planet in a 3-day orbit around the star. We know how far from the star it is by using the orbital period and the mass of the star. We know the mass by how much the star's luminosity is affected.
There is noise in the observations caused by regular luminosity changes in the star, like from sunspots. The larger and closer the planet to the star, the bigger the change in luminosity and the easier it is to separate that signal from the noise. Also the closer planets give more data to work with. If the star has a 72 hour orbit, you will be able to see a complete cycle every three days. If the planet is like Jupiter, it could be 5 AU from the sun and have an orbital period of 12 years.
Their entire reasoning appears to be based on the assumption that a body the size of these 'hot Jupiters' couldn't form that close to the star because the solar wind would drive the gas away. If that were truly the case, then a star couldn't form at all because the solar wind would drive all of its gases away. If the main gas for the planet accumulates prior to solar ignition then there isn't a problem. This new survey only looked for super-Jupiters that are 5 or more times the size of Jupiter, and that are twice as far away from their star as Jupiter is from Sol. The thing is that if a planet gets to be about 13 times the size of Jupiter then it starts to fuse deuterium and becomes a star. We have found many binary stars that would meet the criteria sought, but that don't count because the mass of the "planet" was too big and it became a star.
These are great questions to ask, but I don't know why the media portrays it as such a surprise that things can be like our solar system. Is anyone really surprised that we found water on Mars? Earth has plentiful water, comets are mostly water, Cassini observed water geysers on Saturn's moon Enceladus. Water is simply the combination of the first and third most plentiful elements in our universe, and the second most plentiful element doesn't chemically bond. Water should be the most abundant molecule in the universe after H2.
This article is a good example. It seems to claim that a solar system would need a planet like Jupiter for there to be life. In one paragraph they say that Jupiter prevents the inner planets from being bombarded by too many space rocks, and in the very next paragraph it says Jupiter perturbs the orbit of space rocks to make them hit Earth, seeding it with water and organic molecules. We don't know enough about formation of planetary systems to say that one would need a Jupiter-like planet for life to form. It sounds like the people that claimed 20 years ago that planetary systems would be very rare before we found our first extrasolar planet (we've found hundreds now).
I'd like to see the whole paper and look at their models. I'd like to know what would cause a planet that formed over millions of years in the outer solar system to move in closer to the star. When it forms, it has an orbital velocity relative to the center of gravity of the system. In order to migrate closer to the star, some other massive object would have to slow it down, wouldn't it?
As a working scientist: no he (colmore) didn't. Although his intentions were good.
In science you make some assumptions when creating your theory, but if you find evidence that indicates those assumptions are likely false then it's time to make a new theory. That INCLUDES such assumptions as the universe being consistent.
An excellent example of just that idea is quantum mechanics. The universe, it seems, isn't consistent in quite the way that classical physics thought it was: a cause doesn't always produce the same effect. When we discovered this, we designed quantum mechanics to take this aspect into account.
Both you and colmore use the word "prove." Science is not about proving things, and of course you cannot prove assumptions, or anything else, for that matter. In science there is no proof, because there is always the possibility that you will find a counterexample.
which is then savagely generalized to come up with the unwarranted conclusion that systems like ours are rare. They've got 250 systems observed, wrote a model to match that observation, then decided that the computer model is now the new thinking behind planet formation. It's only a computer model, and we have billions of more datapoints to collect. It ain't time to generalize yet.