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Space Science

Worlds With Two Suns May Sport Black Plants 211

Posted by CmdrTaco
from the try-explaining-that-one dept.
sciencehabit writes "If Tatooine were real, it would probably be filled with black plants and trees. A new study finds that, to maximize energy absorption for photosynthesis, the flora on worlds that orbit two suns may have evolved to use one or more types of light-absorbing pigments that absorb across a broad range of wavelengths, which would tend to make the plant appear black or gray. Although the idea that planets that could host such life may sound far-fetched, such orbs may not be so rare: The team's computer simulations indicate that Earth-like planets can exist in several types of stable orbits in multistar systems. More than one-fourth of the sunlike stars in our galaxy and about half of the long-lived but dim, cool stars called red dwarfs are found in solar systems containing two or more stars, the researchers note."
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Worlds With Two Suns May Sport Black Plants

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  • by dr-suess-fan (210327) on Tuesday April 19, 2011 @03:45PM (#35873382)
    You mean like the plants on Gilligan's Island ?
  • Black Pants (Score:5, Funny)

    by StikyPad (445176) on Tuesday April 19, 2011 @03:47PM (#35873410) Homepage

    Anyone else read this as "Worlds With Two Suns May Sport Black Pants?"

    • by Megahard (1053072)
      That's the intergalactical punishment for lying - forced to wear black pants on a world with two suns.
    • Anyone else read this as "Worlds With Two Suns May Sport Black Pants?"

      Worlds With Two Suns
      May Sport Black Pants;
      the Scientists have said:
      " that world's gone to plaid!"
      and started on a Slashdot rant.

    • by jamesh (87723)

      I did, even after I re-read it several times. I was imagining alien beings trying to look slimmer while being lit from two directions at once or something...

      • by dgatwood (11270)

        I read it that way too. Twice. It's a page design problem, or more precisely three: the use of a sans serif font, insufficient letter spacing that causes the "P" to run into the "l", and using white text on green.

        Amusingly, if we lived on a planet with two suns that had black plants, we might never have discovered the color green, and the text might have been more readable.

    • I saw "Black Planet", which reminded me of Public Enemy and Sisters of Mercy. Somebody needs to mash that up.
    • by Darinbob (1142669)

      I read it that way. I thought "that's stupid even for slashdot", and thus clicked it to read :-)

    • Me too which I thought was funny. But for some reason, you get the mod points and the original poster got modded "troll". Go figure.

  • If you have over-abundance of light, why would you need extra absorption? That's needed when you have LESS light than the earthly average. Also, this implies the planet's life evolved exactly like Earth's for billions of years, which is impossible.
    • by mcmonkey (96054)

      Wouldn't plants in a single-star system also maximize energy absorption? It's not like plants support the stars, so plants in multi-star systems don't need more energy than plants in single-start systems.

      Do you think fish in the ocean maximize water usage more than insects in the desert?

      • Having more energy available in a larger spectrum means that having more pigments might payoff. Plants on earth absorb in the red and blue ranges, adding a third pigment to absorb green generally seems to cost more energy than is gained (remember, it takes energy, materials, and space to construct those pigments). If you have two stars with different spectral signatures, there's a larger energy payoff by having a larger diversity of pigments, and a larger diversity of pigments means more frequencies absor

        • No. Exactly the opposite. With two suns, there is abundant light energy kicking around, so there's no need to absorb a wider spectrum. Thus the plants will use LESS pigments and appear brown and yellow.
          • by Rakishi (759894)

            The amount of energy available is independent of the number of stars. Two colder suns or further away would easily provide less energy than one hotter or closer sun. Not to mention that having too much energy means the planet is a hot sterile rock (at least in terms of earth like biology).

            • . Not to mention that having too much energy means the planet is a hot sterile rock (at least in terms of earth like biology).

              Aww. Why'd you have to go and qualify it? I was gonna call you an "ugly bag of mostly water!"

          • That doesn't make sense. One of the few things that every living species has in common is that it tries to take as much energy as there is available. If these plants evolved in a place with an abundance of energy from an Earth-centric perspective, why would they evolve in a way that doesn't make use of it?

            (One wonders why Earthlike plant life would evolve at all, given the drastic differences that must be introduced by having two suns.)

            • One of the few things that every living species has in common is that it tries to take as much energy as there is available.

              If that's the case, why is feces flammable? Obviously there's still energy there to be had, but the creature couldn't extract it.

              The reason is that it takes energy to develop and maintain systems to extract energy from the environment. If a species can tap into a high energy source, and there is sufficient energy there to grow and prosper and produce offspring, then what's the advantage of expending energy to develop systems to tap lesser energy sources? We humans are, for the most part, diurnal (da

        • Re:Spam (Score:4, Interesting)

          by mcmonkey (96054) on Tuesday April 19, 2011 @04:20PM (#35873766) Homepage

          If you're talking about a system with 2 very similar stars in terms of distance, length of day, intensity, etc.

          But what if one star is dominant? At what point is it not worth harvesting light from the secondary star?

          Rather than black plants that absorb a fuller range of frequencies, you might get 2 parallel evolutionary paths. Green trees would grow tall from the light of the large yellow star, while the underbrush would be full of red leafy ferns which absorb light from the smaller star.

          • by icebike (68054)

            Green trees would grow tall from the light of the large yellow star, while the underbrush would be full of red leafy ferns which absorb light from the smaller star.

            If the large star's light can't penetrate the trees to get to the underbrush, why would the smaller star's light do so?

            • by mcmonkey (96054)

              Because the taller trees absorb the light from the more powerful light source. The light of differing frequencies from the weaker light source aren't worth harnessing (from the trees perspective) and so pass through.

              The underbrush take advantage of what light reaches them.

              Kind of like life in our oceans. Why don't fish at the bottom of the ocean eat the same things fish near the surface eat? Because the surface food doesn't make it's way down to the deep. What falls down to the depths of the ocean is th

        • The pigments are not very efficient: most of the light plants absorb ends up as heat. They have to reflect some of the light to avoid getting too hot and/or losing moisture too fast.

          Give them another billion years and they'll have 90% efficient full-spectrum pigments plus a variable-reflectance surface that they can tune to control leaf temperature.

        • by icebike (68054)

          Stars are either going to be close enough together that both will rise and set very close together, -OR- they will be far enough apart that one appears as a very bright, and the other is too far away to offer enough light for growth.

          Orbital mechanics dictate that you see two close stars, or one close and one VERY distant star.

          In the first case, life supporting planets would have to orbit a common center of gravity of the two planets, and viewed from such a planet, the stars would rise and set together (or v

      • by dwye (1127395)

        > Wouldn't plants in a single-star system also maximize energy absorption?

        Why? Our plants do not maximize energy absorption. Green light reflectivity is actually one of the worst choices that evolution could have made, but it did, and it was good enough, and so filled the ecological niche before a pigment other than chlorophyll developed. Given that chloroplasts probably evolved during an epoch with less light than now, a wide-spectrum of chlorophyll-like light absorbing chemicals would have been even

    • by pclminion (145572)

      If you have over-abundance of light, why would you need extra absorption?

      Competition. If you have two species which coexist, and one of them develops the ability to make use of more of the spectrum, that species will reproduce faster, produce more biomass, whatever. The species which doesn't will be overrun.

      • Re:Spam (Score:5, Insightful)

        by adonoman (624929) on Tuesday April 19, 2011 @04:06PM (#35873606)
        But absorption has to be balanced with water-retention and a host of other factors. If absorbing more of the spectrum is good, then why aren't all plants on earth black? The fact that we see them as green implies that they are reflecting back at least some of the spectrum (it turns out chlorophyll is surprisingly poor at absorbing green light).
        • by drinkypoo (153816)

          It would only be surprising how poor chlorophyll is at absorbing green light if it weren't green...

          • by pclminion (145572)

            It would only be surprising how poor chlorophyll is at absorbing green light if it weren't green...

            It's surprising because the peak of the sun's spectrum is in the green. So the plants ignore the strongest part of the spectrum. That is surprising.

            • It's surprising because the peak of the sun's spectrum is in the green. So the plants ignore the strongest part of the spectrum. That is surprising.

              There's nothing surprising here anywhere for people who have actually thought aout this. Please refrain from confusing your ignorance with some kind of general human lack of expectation of this very result.

              - Some photosynthetic processes benefit from being executed as often as possible. They thus benefit from chemical processes that absorb in the red, because there are many more photons per wavelength interval in the red than in the green (as a matter of fact, in terms of photons per second per area per s

        • (it turns out chlorophyll is surprisingly poor at absorbing green light).

          Why, exactly, is that surprising? Wouldn't that be a given considering how our color-perception works? (Not a flame, I'm genuinely curious and occasionally learn cool stuff even on /.)

        • by Solandri (704621)

          But absorption has to be balanced with water-retention and a host of other factors. If absorbing more of the spectrum is good, then why aren't all plants on earth black?

          The prevalence of green plants in all environments from arid to extremely humid would tend to discount your water-supply based theory. I would assume it's a simple energy balance that's the main culprit. On our planet, the energy cost of evolving/manufacturing a green-absorbing chlorophyll exceeds the energy a plant would get from it. If

      • by slinches (1540051)

        Another possibility are symbiotic relationships between plant species. The higher ones absorbing certain wavelengths and being transparent to those that plants below absorb. This would allow for many color variations instead of just black or gray.

    • James Lovelock's Daisyworld demonstrates what will happen in simple terms.

      If the input of light is "ideal", there will be an equal number of light-absorbing and light-reflecting surfaces, as increasing the number of plants reflecting light will cool the planet below the light-reflecing plant's ideal temperature and vice versa.

      If the light of the planet is high, then the number of light-reflecting surfaces must increase in order for the ecosystem to be stable. Indeed, negative feedback is the only way to MAK

    • by icebike (68054)

      You won't have an over abundance of light.

      Plants evolve to thrive on the light available. You would have nearly the perfect amount, the amount just right for the plant that evolved there.

      Viewing it as if your were an African Violate suddenly transported and trying to cope with a different configuration of suns is the mistake this article makes.

      There is no basis for suggesting one color over another for plants on such a world.

    • It depends on how much light you're getting. E.g., since the specifically mentions dwarf stars, those actually radiate a lot less energy than the Sun.

      Plus, generally, don't think having twice the Earth's energy input (which seem to be the underlying assumption in all the "why black" posts), because then you also wouldn't have liquid water and thus life. Messrs Stefan and Boltzmann say that radiated energy flus is proportional to the 4'th power of absolute temperature, and basically you achieve equilibrium w

  • keep in mind that results from simulation is accurate only if the models used are valid and complete.

    • Obsess about AGW much?
       

      • > Obsess about AGW much?

        Evidently you do, yes.

        • Plants could be one color when one sun was up, then turn a lighter color as both suns were illuminating the area they're in. Then they wouldn't need to evolve, they could just maintain a dynamic equilibrium. So these planets would just be overrun with these weird plants, they'd never evolve televangelists to tell them that they didn't evolve from apes.
  • why's it always got to be about race with you guys? can't we just get along?

  • I imagine it would also mean that any life that evolved there would evolve an eye that would be capable of seeing a broader spectrum of light as well, though, so the plants wouldn't look black to them.

    Still, it's cool; worlds with black & grey plants. Very Star Trek.
    • Good point. There's nothing about red, green, and blue that says they have to be the primary colors of visible light; the fact that we perceive them that way is a function of the way our cone cells work. IIRC, there are birds that can see four primary colors, while various mammals (e.g. dogs) are not actually "colorblind" but only see two primary colors, which makes their range of color perception more limited than ours. On a world with two suns having different spectra, you'd expect animals to evolve ey

    • by vlm (69642)

      I imagine it would also mean that any life that evolved there would evolve an eye that would be capable of seeing a broader spectrum of light as well, though, so the plants wouldn't look black to them

      Water vapor in air is our primary limitation, not solar spectrum. Look at the electronics guys who try to transmit data thru the air using light... Aside from any safety concerns, they all seem to converge on red wavelengths. The atmosphere is a pretty good attenuator above UV and below red. At "long" distances its a pretty poor blue conductor due to scattering.

      I would predict animals in a desert should have a wider eye spectral response than marine animals.

      • by vlm (69642)

        I hate to follow up to myself but I forgot another very important limitation... Look at the optical resolution vs wavelength equations for a given eye size.

        Examine our solar spectrum at the top and bottom of the atmosphere.

        http://en.wikipedia.org/wiki/File:Solar_Spectrum.png [wikipedia.org]

        Below 400 or so nM is a waste of time due to oxygen adsorption. Above 800 nM or so is a waste of time due to water adsorption.

        Why do we have no / very few animals using the bright rnages around 1100 and 1200 and 1600? To get the same

  • by scharkalvin (72228) on Tuesday April 19, 2011 @04:00PM (#35873534) Homepage

    The problem is that most of the stable orbits for a planet in a binary system result in very hot temperatures for part of it's orbit and freezing for the rest of the orbit.
    1: planet orbits one of the two suns and is between two suns for part of orbit.
    2: planet orbits both suns in a highly elliptical orbit taking it in and out of the 'goldilocks' zone where liquid water can exisit.
    3: planet orbits both suns in a figure 8 orbit with similar results to #2

    If BOTH suns are small and close together the planet could orbit both at a 'just right' distance to allow liquid water, but might be too close to the suns and be rotation locked with days and nights 1/2 a year long (like our moon).

    • by H0p313ss (811249) on Tuesday April 19, 2011 @04:06PM (#35873614)

      The problem is that most of the stable orbits for a planet in a binary system result in very hot temperatures for part of it's orbit and freezing for the rest of the orbit.

      So a lot like Canada then?

      • by mdielmann (514750)

        Yes. It's unknown if life there will politely mock Americans, but given the dual nature of their system, a passive-aggressive attitude seems likely.

    • by vlm (69642)

      It helps if the two stars are like Pluto distance apart.

      Even Jupiter distance apart is "not entirely awful". That would make life on Mars very exciting, for example.

      But yeah if Venus and Mars were both Sol sized stars we'd be pretty much screwed, yeah.

    • It would be extremely difficult to find a stable orbit for a planet in such a system. It would require not only that but that the goldilocks zone always overlap the entire planet at all times within the system's cycle. The evidence from our own solar system also suggests that the necessary criteria for life rarely arise from what could be called "simple" planet formation. Venus and Mars formed by simple accretion, both are in the goldilocks zone but neither has the necessary composition to sustain life. Ear

      • by dryeo (100693)

        I've never heard that Venus and Mars don't or didn't have the necessary composition to sustain life. As far as I know Mars currently has the correct composition and Venus before the runaway greenhouse affect started may well have been covered in oceans with tectonic plates and the correct composition.

        • by jd (1658)

          Mars' core turned solid too early on. Well, almost solid. It can't be completely solid as there's an extremely weak magnetic field. The core remains totally liquid on Earth due to heat from nuclear fission within the core. Venus' lava flows are extremely liquid, very low viscosity, resulting in wide, relatively thin layers in all areas that have been mapped (mapping Venus is hard) and no cone structures. A lack of any kind of significant mountain-building, despite considerable tectonic activity, likewise in

    • What's your point?
      Do you think that the planet freezing solid for 10 years then coming to a point where there's a year long summer would mean life were impossible? I'd argue that it would simply lead to a very interesting sort of life. If it has a large moon to keep the core molten life could stay bellow the permafrost until the spring. It's be a very interesting planet indeed.
    • by jmv (93421)

      I'm not an astrophysicist, but I can't really see how cases 1 and 3 could result in a stable orbit. It seems to me like both of those would result in a collision with one of the stars sooner rather than later. The only stable orbit I can see is for the planet to be much further from the stars than the distance between the stars. I assume that would also mean too cold unless the stars are very bright, in which case most of the light would be in the ultraviolet range, which has its own set of problems.

  • teamâ½ Â s (Score:2, Insightful)

    by Eunuchswear (210685)

    Wah?

    • by rehabdoll (221029)

      yeah..

    • Off topic so I'll delete my karma bonus for this post but... Your sig interested me so I researched it. And while I don't claim to side with Ms. Rand, she didn't actively seek Medicare/Social Security--in fact, she fought against getting it but, after several arguments, gave in and simply gave her power of attorney to a loved one who signed her up. The relative assumed it was "ok" because "she paid into it..."
  • There's no mention of how this would affect animal life. Skin tones and fur/feather coloring would be lighter to reflect more of the light, right?
  • Earth's primary photosynthesizers used to be purple; which would make sense since the suns output peak is in the yellow range, so that would be the frequency you'd want to absorb. One theory claims that green plants evolved to take advantage of the light these organisms weren't.

    In other words: it's not that simple.

    • So, there was a photosynthetic war over green and purple?

      Maybe that explains a lot about the Drazi onboard Babylon 5.

    • by jd (1658)

      Another explanation is, as in the Daisyworld model, the balance between green and purple is just right to maximize the benefit for both. Cooperative evolution.

      • by nedlohs (1335013)

        Have you looked outside? Purple got the short straw on that bit of cooperation.

        • by jd (1658)

          I dunno. Purple works for some cabbages and there's plenty of varieties of tree that do well with red-to-purple leaves. There's red and purples photosynthesizing algae. Purple's out there, it's significant in biology, it just isn't dominant at the moment. I rather suspect purple was a lot more common during the Ice Age.

          • by nedlohs (1335013)

            There's not enough of it for them to have gotten their fair share in that "cooperation" though. And of course those green decidious trees mock them every fall...

  • by Weaselmancer (533834) on Tuesday April 19, 2011 @04:24PM (#35873802)

    A new study finds that, to maximize energy absorption for photosynthesis, the flora on worlds that orbit two suns may have evolved to use one or more types of light-absorbing pigments that absorb across a broad range of wavelengths, which would tend to make the plant appear black or gray.

    If that is true, why don't we have black plants here? If you had multiple types of light absorbing pigments in a plant here, that plant would capture more energy from the sun and be able to out compete other types of plants. It would stay well fed in all seasons and would be able to use that extra captured energy to make seeds and reproduce year round, not just once or twice a year like other plants.

    • > If that is true, why don't we have black plants here?

      Probably because light is not the limiting resource.

    • by jd (1658)

      Because totally black plants would increase the temperature of their local environment, thus inhibiting them by more than they would otherwise gain. You've got to look at the whole system, not an isolated fragment.

      • A perfectly reasonable answer, and a point I missed. Thanks.

  • Why would a plant, a leafy plant, want to turn black and live on Tatooine, with a bunch of 3-foot-tall Jawas? That does not make sense!

    But more important, you have to ask yourself: What does this have to do with this post?

    Nothing. Ladies and gentlemen, it has nothing to do with this post! It does not make sense! Look at me. I'm a commenter on a computer geek chat board, and I'm talkin' about black plants! Does that make sense?

    Ladies and gentlemen, I am not making any sense! None of this makes sense! And so

  • Editor is missing the point that Tatooine didn't have any plants or trees at all.

    • by demonbug (309515)

      Editor is missing the point that Tatooine didn't have any plants or trees at all.

      Sure they did. Plants were visible in frame 18720 of the 2003 DVD release of Episode IV. In fact, they were clearly visible for a full 27 frames, but I think you will find they are in the best focus in frame 18720. Frame 18728 is actually better in the most recent release, but I don't think anyone really uses those as a benchmark.

      Just kidding... or am I?

      • I've been all over this fangalaxy, seen some pretty strange things, but nothing that would make me believe that the editor is that kind of fan. Sure, those people exist, he's just not one of 'em.

  • I call BS (Score:5, Interesting)

    by labradore (26729) on Tuesday April 19, 2011 @04:44PM (#35874030)

    Evolution causes mother nature to be very efficient in her selection of characteristics. It might just be that green is useful to plants because it is the right wavelength for efficient photosynthesis with the sun's light. It might be green because it's much easier for plants to make green chloroplasts than other colors or because green imparts enough energy without overheating the leaf structure or its easier for plants to repair green proteins than other colors. If you read up on it a bit, you find out that green does not really maximize energy production, but it's apparently optimal for most plants. However, there's plenty of earth plants that aren't green! Surprisingly there's few black plants. We think too often about optimizing a single parameter. Usually that parameter is short term cash flow. The natural world is a more-or-less true form of capitalism and it's brutal but it shows us that short-term gain isn't the only thing worth maximizing and in nature there's no way to externalize costs for the long-term. Those that do, don't survive.

    • It might just be that green is useful to plants because it is the right wavelength for efficient photosynthesis with the sun's light.

      If that were the case they would absorb green light. They don't. They reflect it while absorbing red and blue. That is why they are green.

      • He's missing a word or two. Try reading it this way:

        It might just be that green (chloroplast) is useful to plants because it (uses) the right wavelength for efficient photosynthesis with the sun's light.

        If you read the rest of his post, it's obvious he's talking about the colour of the chloroplast, not the wavelength of light it absorbs

  • Those plants would be seriously goth.

  • But then if there were two suns, it would also affect our eyes, hence re-defining the color black and green.

    • by PPH (736903)

      Black would still be black. All wavelengths are absorbed.

      As far as green goes, take my wife to the paint store and try to agree on colors. This confirms my hypothesis that she is from a different planet (solar system, actually).

  • Stupid astronomers (Score:4, Informative)

    by nedlohs (1335013) on Tuesday April 19, 2011 @06:05PM (#35874792)

    Plants don't "maximize energy absorption for photosynthesis" on Earth so why leap to the assumption that they would elsewhere. In fact Green is just about the worst color (lets ignore white) they could use on Earth. And retinal exists and is much better than chlorophyll in terms of using the "right" part of the spectrum to get more energy from sunlight (though I think it's then less efficient at harnassing it).

    And of course absorbing too much energy can be a bad thing, heat is an unavoidable product (the atronomers should know that at least, thermodnamics is pretty important to their field...).

    Evolution does not produce perfection, it creeps toward local maximas in the fitness space - OK now the biologists can call me stupid :)

  • A new study finds that, to maximize energy absorption for photosynthesis, the flora on worlds that orbit two suns may have evolved to use one or more types of light-absorbing pigments that absorb across a broad range of wavelengths, which would tend to make the plant appear black or gray

    Dear summarizer: please rtfa. There was no "new study". This was just some people hypothesizing and reasoning. And then they did a computer simulation which had nothing to do with the color of the plants, but rather, a feasibility test to see if plant-like things could even grow in such conditions.

    The team’s computer simulations indicate that Earth-like planets can exist in several types of stable orbits in multistar systems (inset).

    The summary makes it sound like we sent a probe to plant-inhabited planets or something. =P

  • Is one of those stable orbits a stationary position between to stars that circle each other, with poles that are deserts and an equator of icy mountains? Because I wonder what Rabbibunny stew tastes like.
  • Regardless of number of stars the plants pay a tradeoff in energy gathering vs cost of gathering. Plants that are better will displace those that aren't (evolution). Plants on earth have been evolving for a long time, therefore their solutions are likely optimized (for that environment). I therefore expect alien worlds will have green plants, insects, birds and fish.
  • Hence leaves on earth plants are mostly green. The green yellow wavelengths from our sun are the most powerful, earthy chlorophyll wants infra-red so the leaf bounces the green (and yellow) away.

    Incidentally this dovetails quite nicely with the question: why are there no green stars (answer - there are, but to us they look white).

  • "Hey, Stephen Jay Gould, you there? Yeah, they're talking evolution on Slashdot. They seem to think organisms always adapt perfectly to their environments. Heh, yeah, I know, right? Okay, I'll tell 'em you said that."

    We do not inhabit a perfected world where natural selection ruthlessly scrutinizes all organic structures and then molds them for optimal utility. Organisms inherit a body form and a style of embryonic development; these impose constraints upon future change and adaptation.

    -- Hen's Teeth a [amazon.com]

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