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Space Science

Where Would Earth-Like Planets Find Water? 168

Posted by Soulskill
from the at-the-water-store-duh dept.
astroengine writes "The term 'Earth-like worlds' is a vastly overused and hopelessly incorrect term that is popularly bandied about to explain some recent exoplanet discoveries. Although some of the distant small worlds being discovered by the Kepler space telescope may be of Earth-like size, orbiting their sun-like star in Earth-like orbits, calling those worlds 'Earth-like' gives the impression these alien planets are filled with liquid water. It turns out that we have only a vague idea as to where Earth got its water, and it will take a long time until we have any hint of this life-giving resource on worlds orbiting stars thousands of light-years away."
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Where Would Earth-Like Planets Find Water?

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  • by elrous0 (869638) * on Friday December 30, 2011 @03:32PM (#38541404)

    The whole nonsense of even using the term "earth-like" is a joke, born of the press and PR-minded astronomers. Calling a planet "earth-like" implies way more than correlation with earth's size and it's orbit around the sun. There are so many characteristics which may well make the earth a very unique planet. It's not just the presence of water, either--it's also our magnetic field, the presence and effects of our moon, the nature of our core, etc. It could very well be that true earth-like planets are VERY rare in the universe. Though the shear size of the universe suggests it's likely there are other planets out there like ours and other life out there, it's probably a LONG way to our nearest earth-like neighbor--and likely a much longer way than even that to the nearest planet with similar intelligent life living coincidental with us.

    Much as I hate to say it, having grown up on space dreams and science fiction, the more I learn about space the more I've become convinced that, for all intents and purposes, we're basically alone on this little blue ball. When I used to dream otherwise, I really had no real appreciation of just how vast and empty space really is, for one thing. I think the popular perception is that the next solar system begins close to the edge of our own (I certainly thought so when I was a kid watching sci-fi movies). In reality, every solar system is a tiny isolated island in a giant lonely ocean. A space probe that takes 9 years to go from earth to Pluto would take over 100,000 years to get to even our closest neighbor, a mere 4.2 light years away. And that's in a universe that's 15 *billion* light years across. It's a big place, with an unimaginable number of other planets. But mostly it's just a giant, empty void.

    So there are probably indeed other earth-like planets out there. But barring some incredible technological advances (probably thousands of years worth) and a complete overthrow of Einsteinian physics, no human is ever going to see them or even be able to communicate with them.

    This is usually the part where I make a joke, but somehow I just feel lonely and sad now.

    • This is usually the part where I make a joke, but somehow I just feel lonely and sad now.

      Maybe this will do - one of my old sigs:
      "Space - it's really big. I mean, really, really, really big. Better pack a lunch."

      • Re: (Score:2, Funny)

        by Anonymous Coward

        You'd need to pack a fully self sustainable colony. Lunch would barely get you to orbit.

    • by drewsup (990717) on Friday December 30, 2011 @03:44PM (#38541518)
      ... but somehow I just feel lonely and sad now.

      Welcome to /.
    • by khasim (1285) <brandioch.conner@gmail.com> on Friday December 30, 2011 @03:45PM (#38541530)

      How about a basic classification scheme for planets?
      http://en.wikipedia.org/wiki/Class_M_planet [wikipedia.org]
      Except do it better. World size, composition, orbit, etc.

      Then, instead of reporting about another "Earth-like" planet they could report on a class blah-blah-blah-blah planet that MAY be "Earth-like".

    • Well I don't think it is as much earth is unique, as all planets are unique. Saturn is nothing like mars, which is nothing like neptune. I do also have to point out the quanity of planets we can observe, is pretty darn negligable by comparison to how many we estimate there are. Estimated planets in the milkyway, probably billions, number of galaxies that could also have billions of planets, also billions. Number of planets/dwarf planets close enough that we could possibly land a probe on in our lifetime 9.
    • by Anonymous Coward on Friday December 30, 2011 @03:51PM (#38541584)

      The whole nonsense of even using the term "earth-like" is a joke, born of the press and PR-minded astronomers. Calling a planet "earth-like" implies way more than correlation with earth's size and it's orbit around the sun. There are so many characteristics which may well make the earth a very unique planet. It's not just the presence of water, either--it's also our magnetic field, the presence and effects of our moon, the nature of our core, etc. It could very well be that true earth-like planets are VERY rare in the universe.

      Or it could be that we're _not_ so lucky, that these are fairly common, or turn out to be much less essential than we thought. Since we can't measure those remotely (yet), we have no way to stake a solid claim either way.

      So what's wrong with "Earth-like" when referring to planets of which every parameter we _can_ remotely measure at present (thus all the ones we _know_ are scarce) match? Only illiterate fools would choose to infer similarities that we couldn't possibly know from that, and frankly they'll misunderstand no matter what terminology you use.

    • by gmuslera (3436) *
      The sad part is that is not a joke. Is a story we think we are into each time we see at the stars: somewhat, something is out there, very interested in us, and if we advance enough, we could be like them and be interested in someone else that should be within our reach, in our time or not very far enough.

      The magnitude of distances, time and cost that even thinking in getting near the closest star outside this solar system implies is simply outside our reach, and will be for long time if ever, unless our cur
      • by betterunixthanunix (980855) on Friday December 30, 2011 @04:03PM (#38541708)
        Spreading ourselves around the solar system might be a good idea insofar as it will reduce the probability that we kill ourselves. However, the resources that would be required just to set up a permanent colony on the moon are enormous, and there are a lot of other pressing needs competing for those resources. Frankly, I would not be surprised if the manner in which those resources are obtained triggered the sort of species-destroying war that setting up the colony was meant to mitigate.

        For the near future, this planet is it, barring substantial improvements in technology. If we need to choose between a billion dollars spent establishing a colony on a celestial body or spent on developing sustaining methods of producing food in impoverished nations, the production of food must take precedence.
        • Re: (Score:3, Insightful)

          by lacaprup (1652025)

          If we need to choose between a billion dollars spent establishing a colony on a celestial body or spent on developing sustaining methods of producing food in impoverished nations, the production of food must take precedence.

          I fail to see why the food needs of impoverished nations is more significant an issue for wealthy nations than the establishment of a permanent colony on another celestial body. The long-term viability of our species is far better served by expanding than trying to feed every child in the Sudan.

          • by icebraining (1313345) on Friday December 30, 2011 @06:58PM (#38543384) Homepage

            That assumes the priority of the wealthy nations is the long-term viability of our species. Considering the number of policies implemented that jeopardize the long term sustainability for the short term profit, I doubt that is the case.

            I predict we will continue to waste that money in stupid bullshit instead of doing either.

          • by lennier (44736)

            I fail to see why the food needs of impoverished nations is more significant an issue for wealthy nations than the establishment of a permanent colony on another celestial body. The long-term viability of our species is far better served by expanding than trying to feed every child in the Sudan.

            But what if one of those Sudanese kids is the one who will crack the equations for hyperspatial wave motion wormjump planoforming, huh? Huh? And you let her starve in order to build Trans-Plutonian Probe 534 and now you'll never get off this rock.

            This delicious, watery, breathable, edible, sun-drenched rock full of biodiversity. Mmmm, rock.

        • by WSOGMM (1460481)

          For the near future, this planet is it, barring substantial improvements in technology. If we need to choose between a billion dollars spent establishing a colony on a celestial body or spent on developing sustaining methods of producing food in impoverished nations, the production of food must take precedence.

          The thing is, we don't get to choose between a billion dollars spent here and a billion there. IMHO before we can even argue about where money gets spent, we, as a country (I'm referring to the US, you said dollars :P), need to get our priorities straight. As a country we have access to an absolutely HUGE amount of money; we just need to take it. With the proper government in place, we could advance our quality of life AND our [space] technology without even having to choose one over the other. It would, u

    • Re: (Score:3, Funny)

      by Anonymous Coward

      Let me cheer you up with a quote from the Hitchhikers Guide to the Galaxy...

      POPULATION OF UNIVERSE : None.

      It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in it. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From

      • by elrous0 (869638) *

        I remember the old joke about aliens visiting earth, only to send a report back to their home planet that said "No intelligent life found here."

      • by nedlohs (1335013)

        It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in it. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds.

        It is known that there are an infinite number of integers, simply because there is no maximum integer. However, not every one if them is even. Therefore, there must be a finite number of even integers.

        We hit a major flaw with the logic on the very first inference. Of course

        • by Longjmp (632577) on Friday December 30, 2011 @06:48PM (#38543296)
          Wrong on both accounts.
          There are actually twice as many even numbers than odd ones.
          Proof:

          Assume any even number "n", so
          n * n = [even]
          n * (n-1) = [even]
          n * (n-2) = [even]

          Now take any odd number "m":
          m * m = [odd]
          m * (m-1) = [even]
          m * (m-2) = [odd]

          So out of any two odd/even numbers you can generate twice as many even numbers compared to odd numbers.
          q.e.d.

          (and yes, for the non-maths out there, it is a joke)
        • It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in it. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds.

          It is known that there are an infinite number of integers, simply because there is no maximum integer. However, not every one if them is even. Therefore, there must be a finite number of even integers.

          We hit a major flaw with the logic on the very first inference. Of course comic science fiction isn't supposed to be a math textbook.

          Things approach infinity at different rates. As you limit x infinity in y=x^2, y also approaches infinity. If you do the same with y=e^x, y also approaches infinity. The difference is though, that e^x approaches infinity considerably faster than x^2.

          Infinity == Infinity
          infinity !=infinity
          infinity > infinity
          infinity -100000000 > infinity.
          infinity infinity

      • It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in it.

        Is there an infinite amount of space in our spacetime?

    • by ThorGod (456163)

      It could also be that life, as we know it, is not the only way that life can exist. Maybe the factors we find so key (liquid water, planetary e&m field, etc) are more like the specifics of our own existence than the specifics of all existence.

      Yes, "earth-like" is a misnomer and short sighted. But, believing we know the true nature of life across the universe is a whole other category of short sighted.

      • by elrous0 (869638) * on Friday December 30, 2011 @04:08PM (#38541780)

        I think the trouble with finding truly alien life wouldn't just be the distances involved, communication, etc. I think it might prove difficult for two radically different alien lifeforms to even PERCEIVE one another. Sort of a "Sir, it turns out that those things we thought were rocks were actually intelligent lifeforms that just move REALLY slow" kind of thing.

        • by owlstead (636356)

          In the end, we will use the same senses, so I'm not that worried about that particular problem. If it is advanced enough, it will have radio, lasers etc. Why wouldn't it? Because their "eyes" are on a different wavelength? I cannot receive radio either, not without my cell phone anyway.

    • we'll find it by surprise, in some ferrous sulfate or ammonia based medium, or whatever:

      http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry [wikipedia.org]

      in terms of random chance, water is the most accessible medium for complex chemistry, and therefore life to evolve in, by orders of magnitude. however, it's not the only medium that can work, so there's plenty other little nooks and crannies to look into

      basically, some chemists and physicists should get together, and say: for pressure X and temperature Y, sol

    • just doesn't sell the papers so well.

    • by h5inz (1284916)
      Usage of a term depends on it's definition. So where is it?? In your post or somewhere?

      There is such a term like Earth analog which is the synonym for Earth-like planet (I found it in Wikipedia and the first poster should try using it), there are no good specifications inside that specific article, although the round talk under "Attributes and Criteria" is quite similar to the above posters.

      http://en.wikipedia.org/wiki/Earth_analog#Surface-water_and_hydrological_cycle [wikipedia.org]
      How about somebody define it then?

    • [quote]And that's in a universe that's 15 *billion* light years across. It's a big place, with an unimaginable number of other planets. But mostly it's just a giant, empty void.[/quote]

      Yakko: Everybody lives on a street in a city
      Or a village or a town for what it's worth.
      And they're all inside a country which is part of a continent
      That sits upon a planet known as Earth.
      And the Earth is a ball full of oceans and some mountains
      Which is out there spinning silently in space.
      And living on that Earth are the plan

    • by equex (747231)
      I pretty much have the same story as you. Early believer, but then I came to realize the the dimensions of space and how slow our spacecrafts are. On top of that, it seems unlikely that, due to time dilation, any travel by current and near future physics will be moot. I am saying even if you can travel at 10% light speed or a hundred thousand times that, when you come back, everyone you knew will be dead and your research could be completely worthless. Sad but true.
      • I am saying even if you can travel at 10% light speed or a hundred thousand times that,

        A hunrded thousand times 10% is 10,000. If we could travel 10,000 times the speed of light, we could cross about 4-5% of the galaxy in one year.

        • Diameter, not radius. The Milky Way has a diameter of 100,000-120,000 light years, so that would be 8-10%.

          http://en.wikipedia.org/wiki/Milky_Way [wikipedia.org]

        • A hunrded thousand times 10% is 10,000. If we could travel 10,000 times the speed of light, we could cross about 4-5% of the galaxy in one year.

          By your clock, all you need is 99.99% of the speed of light to circumnavigate the known universe. You'd have to forget about anyone you'd left behind on Earth, though.
          • 0.9999c only gets you a factor of 71. Besides, the GP did specifically worry about not recognizing earth on your return. Kind of like Charlton Heston in Planet of the Apes

    • by 0xdeadbeef (28836)

      Calling a planet "earth-like" implies way more than correlation with earth's size and it's orbit around the sun.

      Actually, no, that's about it. The problem is people are screwing that up.

      no human is ever going to see them or even be able to communicate with them

      Yeah, wrong [nasa.gov]. And communication is trivial for anything close enough for imaging.

      • by elrous0 (869638) *

        When I said "see them" I didn't mean through a telescope, I meant "see them in person" as in "go there." Also, if you believe Einstein, and you realize that the nearest planets with coincidental intelligent life using radio waves could be hundreds of thousands of light years away (if not millions), how exactly do you propose communication? About the only message you could send would be "By the time you get this message, our species will probably be long gone."

    • by Genda (560240) <mariet@@@got...net> on Friday December 30, 2011 @05:20PM (#38542472) Journal

      Don't feel bad. It just means we're responsible for becoming the extraterrestrials. We need to seed the universe with humanity (and as many other intelligent species as we can can help get liberated from this little mud ball.) There are countless fascinating environments in this solar system alone. Wealth and resources to beggar the imagination. With a commitment to space faring, we could have sustainable habitats all over the solar system in this century.

      With the building materials available in the Asteroid Belt, Kuiper Belt and Oort Cloud, we could scatter sentience across the stars. We might master faster than light travel. We might not. We would certainly be able to ensure that whatever cataclysms that befell earth in the near or distant future, sentient life would continue to exist, and the earth's greatest gift to the universe would persist.

      Maybe, one day, millions of years from now, when we fill the Orion arm of the Milky Way galaxy, and have found ways to utilize any kind of matter we come across to sustain ourselves, we will bump into another sentient life form. However, there will be no time when we are alone, because we will have each other.

    • by drolli (522659)

      Moreover, the likeliness of us ever transmitting a signal long and strong enough to have a nonzero chance to be heard is quite small.

      a 1GW 1GHz signal will transmit sth like 10^-4 Photons per second and m^2 in a radius of 100ly

    • by TexVex (669445)

      It turns out that we have only a vague idea as to where Earth got its water, and it will take a long time until we have any hint of this life-giving resource on worlds orbiting stars thousands of light-years away.

      Where does this idea that water might be rare and special come from? Our own solar system is teeming with the stuff. It's on several planets, several moons, many comets, and there's probably a bunch of it locked up in asteroids as well. It's a simple compound of the most abundant element in the

    • by Kjella (173770)

      "earth-like" != twin earth. Some of the planets we've discovered are definitively more earth-like than Jupiter-like. Besides, we have very limited knowledge on what's essential to life. No magnetic field fine, could it be that life here on Earth hasn't bothered with developing radiation resistance because there's practically no radiation? If you drop a lion in the Arctic it's going to die, why hasn't it evolved cold resistance? Because it didn't need to, but a polar bear did. Maybe you can compensate for ha

    • A space probe that takes 9 years to go from earth to Pluto would take over 100,000 years to get to even our closest neighbor, a mere 4.2 light years away.

      Well, I see that as a relief. It means that we're safe for at least another 4.2 years from crashing into any other solar system.

  • by hedwards (940851) on Friday December 30, 2011 @03:43PM (#38541506)

    If it's filled with water, then it's definitely not Earthlike, if the OP is going to be a pedantic killjoy, then at least get the facts right.

    • Papers like to make us dream about these "earth-like" planet - very distant from us.
      Honestly, considering the distance, time to travel, time to communicate and get feedback... Wouldn't it be faster/more feasible/realistic to make our Moon an habitable moon?
      I mean, without waiting for 10^x generations of us...
      • by hedwards (940851)

        Either way we'll need to do that. We'll need some sort of long term base of operations outside of the Earth's gravity well and the Moon is one possibility. Granted it's probably not the most efficient, but it does allow the infrastructure to remain indefinitely.

        At the end of the day, if we can't colonize the Moon, then we can't colonize Mars and if we can't colonize Mars then it's rather unlikely that we'll be able to colonize any other planets as Mars is probably the easiest one for us to do.

  • journalism is intended for easy digestion. criticizing journalism for not getting science accurate is actually a sign you don't understand what the purpose of journalism is

    the constant harping on slashdot against journalism for not getting every technical detail accurate and in context is, frankly, stupid. on YOUR part. unless journalism is lying, or saying things completely misleading and way off base, not being entirely accurate is 100% fine. the purpose is COMMUNICATION, not RESEARCH PAPER ACCURACY

    look a

    • No one expects journalism to give us complete technical breakdowns, but science journalism has a nasty history of not just skimming over important details, but also of out-and-out sensationalism. Take your average report on some hominid fossil discovery, which by the time it gets through the editorial department has a headline "Map Of Human Evolution Redrawn!"

      • right, and that's exciting, and perfect for digestion by those people who will never care or be interested in the accurate details

        so there's no harm. people need a gee whiz component. give it to them. science should not be completely inaccessible

        because, if we abide by your standards of communication, what is said about science by scientists will be ignored: too dry and boring. and what is said in popular media will be taken over by those with anti-science agendas, and their lies and distortions will be bel

        • Oh give me a break. Having a journalist deliberately distorting a report to sell newspapers or banner ads or whatever isn't defensible.

  • by G3ckoG33k (647276) on Friday December 30, 2011 @03:44PM (#38541510)

    "The term 'Earth-like worlds' is a vastly overused and hopelessly incorrect term"

    "Earth-like worlds" is not an incorrect term. Misused perhaps, but not incorrect.

    • by sco08y (615665)

      "The term 'Earth-like worlds' is a vastly overused and hopelessly incorrect term"

      "Earth-like worlds" is not an incorrect term. Misused perhaps, but not incorrect.

      I thought it was pretty correct and well used, in context. After all, a planet outside the temperate zone or that is a gas giant or too small generally can't have liquid water at all, so "earth-like" can easily mean "it doesn't have the factors that obviously rule out life as we know it." And considering the context, which is usually, "we know how big it is and its orbit because we detected incredibly faint wobbles in a far larger star," I think a typically curious layman is going to grasp that no one is cl

  • by hashp (68887) on Friday December 30, 2011 @03:47PM (#38541546) Homepage
    Forgive my ignorance, but why do we always seem to presume alien life has to be hydrocarbon bases like ourselves? Couldn't their metabolism be based on some other chemical process?
    • by Kenja (541830)
      You underestimate the importance of a gin & tonic.
    • by Zocalo (252965) on Friday December 30, 2011 @04:02PM (#38541704) Homepage
      It's not so "presumed" as it is believed to be the most likely basis for complex, multi-cellular, life by a considerable margin due to carbon's versatility in forming the huge number of chemical forms with other elements that necessary for the required biological processes. That said, it's definitely not the only option [wikipedia.org], silicon, nitrogen and phosphorous based biochemisties all being seen as theorerically viable, although silicon is most often seen as the most likely alternative. Here's a (somewhat old) link to Lou Allamandola, an NAI astrobiologist, discussing [nasa.gov] the various merits of silicon- versus carbon-based life.
    • by rts008 (812749)

      To put it simply, it's due to lack of knowledge and/or imagination.
      What we can imagine is defined by what we know.
      For examples, you can look to older Sci-F.
      Jules Verne's artillery shell moon trip, Sir Arthur Canon Doyle's 'Earth passing through vapours in it's orbit and killing people' story, Edgar Rice Burroughs' John Carter of Mars books, etc.

      The more we know, the more we can imagine....

      • by bware (148533)

        To put it simply, it's due to lack of knowledge and/or imagination.

        I object, sir. The people planning these missions are the ones who read those books and devoted their very life's work to the scientific proof of these hypotheses.

        I've sat in the room while these topics are debated, at a high aggregate hourly rate, and we have discussed looking at other sources, non-earth-like planets, non-carbon based lifeforms, telescopes on the moon, telescopes in Jupiter orbit, arrays of telescopes, life on planets arou

        • I think we are on two different pages here.

          I presumed a 'generic-mass public' POV type question that I replied to in that same context...think PR, or KISS for the layman.
          *hint::*

          "Forgive my ignorance,..."

          I feel you have done me a disservice by not not reading my reply in the context of the discussion.

          'In general', or 'Generally' ignores the outliers while being 'good enough' for the laymen that are curious, but don't want to jump into astrophysics, and other studies. That was the spirit of my reply.

          You should not have wasted mod p

    • by v1 (525388) on Friday December 30, 2011 @04:14PM (#38541838) Homepage Journal

      Once life gets going and has managed to develop evolutionary mechanisms such as sex and dna, (neither of which are specifically required) life tends to become highly adaptable and resilient to changing conditions. The problem is getting there in the first place. That first "spark of life" collection of molecules that can reproduce has to happen from an incredibly good stroke of luck.

      The odds of that incredibly rare event happening are made possible by and improved on by favorable conditions. Liquid water, atmosphere, a water cycle, abundant energy, and a magnetic field are all part of that "thumb on the wheel", improving the odds of genesis occurring here on earth.

      But they're not required. The only thing that is probably actually required is a liquid cycle of some sort, to provide a circulation of materials because original life was almost certainly not capable of locomotion, and an abundant source of energy. I've read several papers on a plausible genesis based on a liquid methane cycle.

      Several conditions on earth are probably not even optimal. The low temperature and pressure of our atmosphere for example - someplace more like Venus has an edge on Earth in that respect. Part of why people tend to think of water/carbon as necessary is they are assuming earth's low pressure and temperature. Molecules get a lot more flexible under those different conditions. If you have "water tunnel-vision" you may completely discount a place like venus where liquid water can't really exist in any quantity.

      I think it's fair to argue that some combination of a liquid cycle where the liquid is at a reactive temperature and pressure are probably almost required for genesis. I hesitate to flat out say "required" because a sufficiently lucky turn of events can lead to genesis even in the most apparently unfavorable conditions imaginable. But we can't really get anything accomplished unless we set some constraints on things and try to look at more "reasonable" scenarios. Even though the number of exoplanets in existence is nearly infinite for our practical purposes, it is a finite number, and odds must come into play. Just because there's a ton of planets out there doesn't mean a bunch of them have life. Without any control point of reference it's hard to argue that even just earth in the universe having life was anything but a stroke of incredible luck. We're probably a lot more special than any of us can possibly imagine.

    • by sco08y (615665)

      Forgive my ignorance, but why do we always seem to presume alien life has to be hydrocarbon bases like ourselves? Couldn't their metabolism be based on some other chemical process?

      It's a known problem. We're like the guy looking for his car keys under the streetlight. Yeah, he could have dropped them anywhere but that's the only place he's got light.

    • by khipu (2511498)

      For one, because we observe the building blocks of carbon-based life throughout the universe.

      Furthermore, there are essentially no other choices. There are 81 stable elements, and most of those are metals, halogens, or noble gases--unsuitable for the kinds of complex structures that life depends on. Other than carbon, the only element that conceivably might for the basis for life is silicon, but even that's a stretch.

    • by stevelinton (4044)

      There are some reasons. If you assume that life is based on complex chemistry in the first place (and not say magnetic fields in a gas cloud or electrostatic patterns in clay or naturally evolved electronic circuits or .... -- and here the looking under the streetlight theory applies) then there are surprisingly few choices. To have complex chemistry you need the possibility of lots of kinds of large molecules. Metals don't do that, so you are down to non-metals. If you have mostly atoms that form 1 or 2 ch

  • by wcrowe (94389) on Friday December 30, 2011 @03:53PM (#38541616)

    Finally, some common sense on this. Not only is there the question of water, but also whether a planet has a magnetic field which protects atmospheric loss to it's sun's solar wind. Yes, the term "Earth like" is overused.

    Another overused term is "God particle".

    • Re:Finally (Score:4, Funny)

      by ceoyoyo (59147) on Friday December 30, 2011 @04:06PM (#38541758)

      No. Both are very valuable terms, and should be used more.

      When someone reads an article with "Earth-like" in it and assumes that means this other planet is just like Earth, and comes and tells me about it, I then know that he is an idiot. On the other hand, if someone complains (especially at length) about the use of the term, I know he's pedantic. As a bonus, constant disappointment for the first guy may help him improve his critical thinking skills and general knowledge base, possibly making him not an idiot.

      "God particle" is similar, except that it also elicits outraged statements that reveal the speaker is a crazy religious nut job having a crisis of faith.

      See? Both terms have a habit of revealing useful information about people who see them used, potentially provide educational incentives for those people, AND provide a useful shorthand (well, God particle not so much) for the rest of us.

    • But if the planet doesn't have a magnetic field, maybe the organisms are used to the radiation.

  • not Earth

  • One thing that always gets me about these announcements is the intentional hand-wave regarding the ability of life to spring up in environments that are different than ours. We aren't the only game in town, statistically speaking, and "life" is such an amazingly broad term that simple definitions of it include simple self-replicating systems.

    Personally, I don't think we're the only life in the Universe. There is such a wide variety of chemicals that have come together in some very interesting ways here on E

  • Water is 'out there'....a lot of it. It may not be concentrated where we would like to see it, but it's out there.

  • Water (Score:4, Interesting)

    by robably (1044462) on Friday December 30, 2011 @04:19PM (#38541886) Journal

    it will take a long time until we have any hint of this life-giving resource on worlds orbiting stars thousands of light-years away.

    Doesn't matter. By the time we reach any planets in other solar systems we won't need water to survive. We'll have transferred our brains to computers and will use whatever android bodies are suitable for the terrain.

    I know, sounds fanciful, but it's more realistic than to think that we'll be sending human beings to other solar systems. The amount of oxygen, water, food, and other resources required - even if we invent some kind of suspended animation - makes it laughably unlikely.

  • by bratwiz (635601) on Friday December 30, 2011 @04:20PM (#38541892)

    Where Would Earth-Like Planets Find Water?

    Uh, how about in the ocean..?? Or in the creeks, streams and rivers?

    Or maybe they could just-- you know-- turn on the tap and out it comes.

    You did specify "Earth-like"....

  • "It turns out that we have only a vague idea as to where Earth got its water, and it will take a long time until we have any hint of this life-giving resource on worlds orbiting stars thousands of light-years away."

    I have no idea of water specifically but I thought all/most mater after hydrogen and helium was made by stars.
    But regardless of where it comes from it is a very common material in space so there is little reason not to assume that a planet that has the right conditions for liquid water would not

  • Ha Ha Ha.
    Thanks, I'll be here all week.

    Try the Veal, it's great.

  • . . . caused by global warming . . .

    . . . just like where our water comes from . . .

  • "Like" is Relative (Score:4, Interesting)

    by Bob9113 (14996) on Friday December 30, 2011 @05:13PM (#38542386) Homepage

    The word "Like" is relative. Relative to the past frame of reference. The second time you see a gorilla, you think it looks like the first gorilla. I suspect I would be hard-pressed to tell a male gorilla from a female on casual observation. Jane Goodall, however, probably sees as much visual distinction between individual gorillas as you see between humans.

    Same with exoplanets. The first ones we detected were supergiants in close orbits around relatively small stars. Compared to those, Mars is Earth-like. Now we've found enough that "Earth-like" is evolving to mean something more specific. Vague terms in novel and rapidly advancing fields have evolving meanings. That is the nature of language.

    As others have said, exoplanet taxonomy is a fine new field to plumb, but that doesn't mean Earth-like is bad -- it's just vague and unscientific. A rough measure that only has meaning in context. Conversational shorthand, useful in casual discourse.

    A quick look around finds that there are people working on formal taxonomy. [arxiv.org]

    • The word "Like" is relative. Relative to the past frame of reference. The second time you see a gorilla, you think it looks like the first gorilla. I suspect I would be hard-pressed to tell a male gorilla from a female on casual observation

                I am sure you can find some websites that will clear that right up for you.

  • My theory, based on no actual empirical evidence, is that whatever object struck Earth to make the moon was a large comet. While I'm not sure how this could be proven, it would explain the arrival of the oceans after Earth was formed and after the moon came along. It also explains the subsurface water being found on the moon. It would also mean that "Earth-like" planets take a somewhat rarer series of events to happen.

  • Hydrogen makes up roughly 75% of the Milky Way, by mass, apparently. Oxygen is a little rarer, about 1% of the Milky Way, but it's the third-most common element. When you put the two of them together, they form water pretty readily.
  • We already know it jets out of the star which is being born from the interstellar dust disk. Question answered. Next one, please.

  • Duh (Score:2, Funny)

    by Legion303 (97901)

    "It turns out that we have only a vague idea as to where Earth got its water"

    Read your bible! It's God's piss.

  • Would it not be more feasible to genetically engineer ourselves and other organisms to other planets' environments than to go traipsing around the universe with the faint hope that we find one that is just like ours?
  • No water? Seriously? (Score:4, Interesting)

    by SectoidRandom (87023) on Saturday December 31, 2011 @02:44AM (#38546336) Homepage

    How about what has already been found out there:

    Most Distant Water in the Universe Found [physorg.com]

    and

    Evidence of Water in Atmospheres of Planets Orbiting Distant Stars [pureinsight.org]

    And I hear we've only been doing this planet finding stuff successfully for a little while.

    • The problem isn't the existence of water before the formation of the Sun, it's why it's still here. First, the young Sun would clean the space around itself from excess material with an intense solar wind. The Giant Impact to form the moon would convert the Earth into a magma ocean, again not much helping with water retention. Over time, the solar wind and ultraviolet radiation destroyed the water in all other planets close to the Sun. In the inner solar system, all unprotected water will eventually evapora

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