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Space Science

Earth-Like Planet That Could Sustain Life Found 575

Posted by samzenpus
from the guess-who's-coming-to-dinner dept.
astroengine writes "An exoplanet, 20 to 50 percent the mass of Earth, has been discovered 20 light-years away and it appears to have all the ingredients conducive to sustaining life. It has enough gravitational clout to hold onto an atmosphere and it orbits well within the 'Goldilocks Zone' of its parent star. However, it would be a very different place to Earth; it is tidally locked to its star, creating one perpetual day on the world. Interestingly, this may also boost the life-giving qualities of the exoplanet, creating stable temperatures in its atmosphere."
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Earth-Like Planet That Could Sustain Life Found

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  • Annddd.... (Score:4, Funny)

    by Codename Dutchess (1782238) on Wednesday September 29, 2010 @07:59PM (#33741930)

    This is where I stopped reading:

    "Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that the chances for life on this planet are 100 percent. I have almost no doubt about it," Steven Vogt, professor of astronomy and astrophysics at University of California Santa Cruz, told Discovery News.

    Chances are 100%. Almost no doubt.

    • by durrr (1316311)
      He would've been a douche had he he said chances are 99,9999999999999999999%, like any good scientist he made his argument understandable to the layman by rounding up.
      • Re:Annddd.... (Score:5, Insightful)

        by The_mad_linguist (1019680) on Wednesday September 29, 2010 @08:07PM (#33741990)

        His argument doesn't really hold water. Sure, once you have life that can survive on a planet it's a bitch to keep it away from anywhere, but there's no guarantee that you'll get that life to begin with.

        • Re: (Score:3, Insightful)

          by AmigaMMC (1103025)

          I would say that the chances for life on this planet are 100 percent. I have almost no doubt about it,"

          He contradicts himself: chances are 100%, almost sure. "Almost" is not 100%.

          Plus what's up with Planet G? Planet M would have been better ;)

          • Re: (Score:3, Insightful)

            by h4rm0ny (722443)
            Maybe he has almost no doubt about the chance of life being 100% in the same way that if I'm almost sure that a bus drove off a cliff then I almost have no doubt that there's a 100% chance of it having fallen due to gravity. I.e. our model says the chance is 100% and I have almost no doubt that the model is correct.

            Separately, TFS contradicts TFA. According to TFA, the planet's mass is three times larger than Earth's (I wish they'd just say three times Earth's as three times larger sounds like 1g + 3g to
        • Re:Annddd.... (Score:5, Interesting)

          by rahvin112 (446269) on Thursday September 30, 2010 @04:08AM (#33744622)

          There is an argument to be made that because of the very physics of the universe that life itself may be not only inevitable but practically guaranteed. This statement is made with consideration of organic chemistry and the pervasiveness with which hydrocarbons not only exist but seem to interact and react to other hydrocarbons. Carl Sagan was the biggest proponent of this hypothesis, that the physical laws of the universe predispose the creation of life. If the hypothesis is correct, that hydrocarbons are so common throughout the universe (which they are) and that their interaction to form amino acids and the basis of life itself is the end result of the laws of the universe (supposition at best) then if a planet is the right temperature, has water and carbon then life should form. (note mars isn't warm enough and has no free water and Venus is way way to warm, but Titan is literally covered in lakes of liquid hydrocarbons)

          I agree the guy is a bad scientist for making such a claim, but if you believe this line of reasoning then if you can find a star with planets in the habitable zone, the right size, with water and enough carbon then you will have life "guaranteed". They are just on the cusp of having enough technology to see earth size planets, I think it will be just a mater of time till they can spectrograph the light bouncing off the planet and can find out which ones have oxygen in the atmosphere. Once you find oxygen you know you have life, at least minimal enough life to create free oxygen which can't exist without life because of it's highly reactive nature. I believe Carl was right, that life is an inevitable consequence of the universe, but until we have a better understanding of exosolar planets and that our solar system(and the earth itself with it's super-sized moon and high rotation) isn't unique we don't have the ability to say life is guaranteed anywhere and that's what makes his assertion so silly even if he believes Carl's hypothesis.

          It's an interesting area, because you could test the theory. With some massive expenditures of cash it would be possible to stop the run away greenhouse effect on Venus. Once the planet cooled it would rapidly lose much of it's excess atmosphere and attain a condition not that much different than the early earth except for the very slow rotation and lack of a moon. That test would then prove whether the moon (tidal forces) and fast rotation (short nights) were special or essential in the creation of life. If those two variances are important than life could still be quite rare even with the universal predisposition to life from the right physical circumstances. It's been argued that life first started in the tidal pools on earth, without tides you don't get the periodic flooding that life in the current tidal pools needs to survive. Whether life can survive nights that last multiple days or even weeks is another argument that has little to no evidence to support.

          Anyway, I don't agree with the scientists affirmation but I do understand why he would believe so strongly that life is guaranteed if the conditions are right.

      • by vux984 (928602)

        Yes... 99.9999...% would be stupid, but 100% isn't better.

        He should have just dropped the percentage quantification entirely then knowing that rounding up 'almost certain' to 'certain' glosses over a very important distinction. He could have just simply reported that he is "almost certain the planet will be found to have life" and left it at that.

      • Re: (Score:3, Funny)

        by mikeabbott420 (744514)
        I always thought Spocks ridiculous precision with fuzzy math was really "don't question me you pathetic dummies" because, I mean, for f*cks sake, Really?, that many decimal places of accuracy? ;)
      • Re: (Score:3, Informative)

        by Eivind (15695)

        But realistically, chances aren't ANYWHERE near either number. We simply don't know how likely it is for life to exist on planets with a certain temperature and composition.

        We know there's life on earth. That's a single data-point. Any scientist knows that drawing strong conclusions from a single datapoint is nuts.

        Sure, if we had investigated 23 earth-similar planets, and found life on every single one of them, then we'd have enough data to say that earth-similar planets tend to have life on them.

        But that's

    • Re:Annddd.... (Score:5, Insightful)

      by SETIGuy (33768) on Wednesday September 29, 2010 @09:37PM (#33742700) Homepage

      This is where I stopped reading:

      That's a very appropriate point to stop. To paraphrase Clarke: "When a senior scientist tells you something is impossible, they are likely to be wrong. When a senior scientist tells you something is certain, they are likely to be wrong. When a senior scientist tells you something may be possible, they are probably correct."

      • Yes, we've all heard the quote but it doesn't really apply here. The guy is saying it's not just possible, it's almost certain. And yes, technically you could say 'well he's really saying it's impossible there isn't life there' but that's just being a pedant. Yes, he could be wrong but it's clearly hyperbole. When a scientist says that something is impossible he's rarely being hyperbolic. The meaning and spirit of Clarke's quote is clearly that 'far more things are possible than people/scientists think'.

  • by brunes69 (86786) <slashdot&keirstead,org> on Wednesday September 29, 2010 @08:03PM (#33741960) Homepage

    20 light years is millimeters of astrophysical distance.

    It amazes me we have been observing space so long and yet we only now have detected this planet.

    It just goes to show how incredibly likely it is to find planets like Earth everywhere in the galaxy.

    • by mangu (126918) on Wednesday September 29, 2010 @08:56PM (#33742418)

      20 light years is millimeters of astrophysical distance.

      It amazes me we have been observing space so long and yet we only now have detected this planet.

      This just goes to show you the difference in difficulty between finding a Jupiter-sized planet and an Earth-sized planet.

      • Re: (Score:3, Insightful)

        Pssst. It hasn't been all that long since we discovered our first exoplanet, Jupiter sized or otherwise... 15 years or so. I think we get spoiled by the wonderful advances in science and forget how hard and how much resources it takes to keep advancing.

    • by cgenman (325138) on Wednesday September 29, 2010 @09:03PM (#33742484) Homepage

      20 light years away gives a search area of about 13,000,000,000,000,000,000,000,000 cubic miles. Unless it is spewing massive amounts of radiation all of the time, things like that in that big of a search space are pretty hard to detect. And while 20 light years might be small by astronomical standards, human beings haven't even been two light *seconds* away from the earth.

      • by Penguinisto (415985) on Wednesday September 29, 2010 @09:12PM (#33742540) Journal

        And while 20 light years might be small by astronomical standards, human beings haven't even been two light *seconds* away from the earth.

        FWIW, Voyager 1 is about 14-15 light-hours away now.

        Something to consider, though - not all radiation is the evil, hazardous, cancer-causing flesh-melting variety. Light is radiation, which is, well what they'd been using to study this thing. The shallow end of the details pool can be had here [ucolick.org](pdf).

        Also, they're not just blindly poking around at random bits of cubic space - they're starting with stars, eh?

        • by wvmarle (1070040) on Wednesday September 29, 2010 @10:46PM (#33743116)

          The furthest away from Earth a living human has ever been, is just behind the Moon (orbit around the moon), or about 1.3 light seconds. Indeed humans have some small craft flying around much further away in space, but no human on board there. And still a long way to go to reach 20 light years.

        • by IICV (652597) on Wednesday September 29, 2010 @11:55PM (#33743466)

          Something to consider, though - not all radiation is the evil, hazardous, cancer-causing flesh-melting variety. Light is radiation, which is, well what they'd been using to study this thing.

          The GP poster neither said nor implied anything along those lines, and indeed was clearly using the "light is radiation" definition (among other ones, of course - it's not like our telescopes are limited to the visible spectrum any more). Has Slashdot fallen so low that we actually need to randomly defend the usage of the word "radiation"? I thought most of the people here had a reasonable understanding of science.

    • by TapeCutter (624760) * on Wednesday September 29, 2010 @09:37PM (#33742698) Journal
      "20 light years is millimeters of astrophysical distance."

      Nope, it's 20lys. Astronmers rarely measure interstellar distantances in mm due to the astronomical numbers it involves.
      • Re: (Score:3, Informative)

        by u38cg (607297)
        20 light years = 1.89210568 × 10^20 millimetres. Seems perfectly tractable to me.
  • by way2trivial (601132) on Wednesday September 29, 2010 @08:03PM (#33741964) Homepage Journal

    Really.. I thought life & evolution and development thrived on change...

    a little flooding, many die, some adapt
    a little freezing, many die, some adapt.

    more-- the 'kickstart' of inorganic->organic chemistry, presumably took some random event, a one in five gazzillion possible combination of elements, random elements- that likely would be less likely the more stable an environment it is..

    nice flat temp? ya get algae & molds.... no need to improve right? why?

    • by martin-boundary (547041) on Wednesday September 29, 2010 @08:09PM (#33742012)
      You'd be right only if evolution was merely a function of the environmental conditions. However, your algae and molds will also compete among themselves, leading to adaptation independently of the environment.
    • by jrumney (197329) on Wednesday September 29, 2010 @08:09PM (#33742016) Homepage
      Look at where the most biodiverse regions are on Earth. They are in the equatorial zone, where the climate is stable.
    • Re: (Score:3, Interesting)

      by Xtifr (1323)

      I thought life & evolution and development thrived on change..

      Evolutionary change seems to be enhanced by environmental change, yes, but life itself is an entirely separate matter. Life doesn't have to be complex or evolve rapidly in order to simply exist. In 3.5 gigayears, life on Earth has gone from matted plankton [wikipedia.org] to, well, people. In the same period of time, life on this planet might have gone from matted plankton to really matted plankton. But it would still be life.

      the 'kickstart' of inorganic->organic chemistry, presumably took some random event, a one in five gazzillion possible combination of elements

      Actually, that's pretty much the exact opposite of contemporary thinking; due to the amazingly

  • Summary is wrong. (Score:5, Informative)

    by The_mad_linguist (1019680) on Wednesday September 29, 2010 @08:04PM (#33741970)

    The summary is incorrect. The exoplanet has "a mass three times larger than Earth's", not 20% to 50%

    • Re:Summary is wrong. (Score:5, Informative)

      by martin-boundary (547041) on Wednesday September 29, 2010 @08:23PM (#33742134)
      If the two planets have similar density, then the mass ratio is simply the ratio of the volumes. Volume of a sphere is 4 pi R^3/3. Thus the volume ratio of the two planets is (R + x)^3/R^3 = 1 + 3(x/R) + 3(x/R)^2 + (x/R)^3. If you plot that function, you find that this ratio is between 2 and 3 when (x/R) is between 0.25 and 0.45, so that R + x is about 25%-45% bigger than R.
      • by meerling (1487879) on Wednesday September 29, 2010 @08:43PM (#33742316)
        Who cares about volume or density at this point as both the summary and the article specify mass. The summary says 20%-50% the mass of Earth, while the article says 3x the mass of Earth, that would be 300%. No matter how you look at it, the summary screwed up big time.

        Sorry, but your argument is like calculating the seating capacity of a car when the articles in question are discussing the top speed.
    • Re: (Score:3, Funny)

      by syousef (465911)

      The summary is incorrect. The exoplanet has "a mass three times larger than Earth's", not 20% to 50%

      Disappointing. Kinda reminds you of going on a blind date...

    • by phlegmofdiscontent (459470) on Wednesday September 29, 2010 @11:02PM (#33743202)

      Space.com gives a better summary:

      http://www.space.com/scienceastronomy/earth-like-exoplanet-possibly-habitable-100929.html [space.com]

      However, I think the 20% to 50% number comes from the size of the star, Gliese 581. The mass of the star is 20% to 50% of the sun's mass.

      Thus far, the lowest-massed planet discovered by the radial velocity method was about 150% to 200% the mass of Earth. Discovering one as small as 20% to 50% is currently beyond the capabilities of the RV method, so the 300% to 400% figure makes a lot more sense.

  • by mykos (1627575) on Wednesday September 29, 2010 @08:05PM (#33741980)
    Ethics aside, wouldn't it be easier to genetically modify humans to live in a wider variety of environments? Seems like it would be a far more reachable goal in the near term than getting to these distant planets.
  • Time dilation woes. (Score:5, Interesting)

    by Anonymous Coward on Wednesday September 29, 2010 @08:07PM (#33741994)

    My math might be a little off, but if we accelerated at g half-way there and decelerated at g for the rest of the way, it would only take a ship about 6.04 years to get there. But thanks to Einstein ruining all our space travel fun with relativity, we of us left on Earth would think the journey took 21.86 years. So there and back would seem like 43.7 years to us.

    • by Drishmung (458368) on Wednesday September 29, 2010 @08:45PM (#33742334)
      Assuming the vessel had the mass of the space shuttle, at 1g the energy required to do that would be approximately 2,304,558,096 times the Nagasaki A-bomb.

      m = 104,328kg
      a = g = 9.80665ms^-2
      20ly = 1.89E+17m
      Nagasaki A-bomb = 80TJ.

      • Re: (Score:3, Insightful)

        by pclminion (145572)
        Since you didn't show your math, I have to ask... Did you use the relativistic definition of kinetic energy or the Newtonian one? Because using Newton would be incredibly wrong in this case.
  • Life (?) (Score:4, Insightful)

    by tanujt (1909206) on Wednesday September 29, 2010 @08:09PM (#33742010)
    Just 20 light years away is good news! One thing that always bothers me when I read about E.T. life, is the fact that we get excited when we find water or an Earth-like atmosphere somewhere, thinking there should/might be life there. We should factor in the possibility that life may evolve entirely differently from us, without requiring water or nitrogen/oxygen. In that case though, we can't really know how it will have evolved as we have no reference of evolution other than ours. So let's wait, or just go there as soon as we can as aliens.
    • Re: (Score:3, Informative)

      by Taibhsear (1286214)

      I do agree that other forms of life MAY be possible, but having a background in biochemistry you realize just how important water is to any concept of life to arise. Solubility, reactivity, and relative density properties that are necessary for any life to form are pretty much unique to water.

  • Venus and Mars (Score:5, Insightful)

    by AJWM (19027) on Wednesday September 29, 2010 @08:11PM (#33742034) Homepage

    Venus and Mars are also rocky "Earthlike" planets orbiting roughly in the habzone ("goldilocks" zone).

    I'd like to see truly terrestrial planets as much as (more than, probably) the next guy, but I think the reportage here is a bit hyped. Especially given a ~3x mass, that gives it roughly 1.44x the surface gravity (and higher likelihood of a Venus-like atmosphere).

    • Re:Venus and Mars (Score:4, Informative)

      by mister_playboy (1474163) on Wednesday September 29, 2010 @08:37PM (#33742252)

      Also not mentioned is that Gilese 581 is class M red dwarf star with a radiation output very different from that of the Sun. The lack of UV light and greater amount of infrared light may have implications for the ability for life to develop.

      The star's small power output is why a planet with an orbital period of only 37 days (Mercury orbits in 88 days, for comparison) can be in the habitable zone.

      http://en.wikipedia.org/wiki/Gilese_581 [wikipedia.org]

  • by Joe The Dragon (967727) on Wednesday September 29, 2010 @08:12PM (#33742046)

    Spin up the stargate and dial it!

  • Alien astronomers (Score:3, Informative)

    by Dutchmaan (442553) on Wednesday September 29, 2010 @08:17PM (#33742086) Homepage
    What are the odds that alien astronomers on that world are having their exact same story posted on Alien Slashdot®!?
  • by hyades1 (1149581) <hyades1@hotmail.com> on Wednesday September 29, 2010 @08:21PM (#33742120)

    Well, since the star's only 20 light years away and the previous post noted that the Aussies are testing "Space Beer", you can sign me up for the trip. Maybe by the time we get back the Toronto Maple Leafs will have won the Stanley Cup.

    OK, OK, I'm kidding about the Leafs.

  • by bl8n8r (649187) on Wednesday September 29, 2010 @08:29PM (#33742172)
    intriguing is the fact that we are studying the planet as it was 20 years ago, not as it is present day. In roughly 100 years we've managed to screw up this planet to no end. Things could be quite different on gliese 581g at this moment and we would not know it. Assuming we could travel at the speed of light and made it there in 20 years, the inhabitants may have already turned most of the planet to concrete and smog. If it is indeed inhabited.
    • by Anonymous Coward on Wednesday September 29, 2010 @10:06PM (#33742876)

      intriguing is the fact that we are studying the planet as it was 20 years ago, not as it is present day. In roughly 100 years we've managed to screw up this planet to no end. Things could be quite different on gliese 581g at this moment and we would not know it. Assuming we could travel at the speed of light and made it there in 20 years, the inhabitants may have already turned most of the planet to concrete and smog. If it is indeed inhabited.

      It's intriguing to me that anyone would call cities "screwing up" the planet. We've transformed the environment into one that is incredibly comfortable for our species to live in. There has never been a better time. The real argument that we're screwing up the planet involves this state being unsustainable, not the fact that we've achieved it.

    • Re: (Score:3, Insightful)

      by Anonymous Coward

      The planet doesn't care, we don't matter. In ten thousand years most of what we'd done would be gone. In ten million years most every species alive now will be extinct humans or not. That's nothing in the lifetime of this planet. The natural state of things is change and right now we're little more than an amusing bump in the grand timeline of this planet.

      Stop deluding yourself into thinking we matter or that there's some actual entity called "nature" that cares what you do.

      In the end, the only reason natur

  • temperature (Score:3, Interesting)

    by blair1q (305137) on Wednesday September 29, 2010 @08:36PM (#33742246) Journal

    "Interestingly, this may also boost the life-giving qualities of the exoplanet, creating stable temperatures in its atmosphere."

    I don't get why that boosts life-giving qualities.

    Having unstable temperatures in our atmosphere doesn't seem to have impeded life.

    In fact stable temperatures may be a bad thing.

    It takes instability to produce the mixing of organic molecules that result in biomass. Lightning. Tidal flow. Wind.

    But there's no indication this new planet lacks those. Except the tidal part. Unless it has a big moon. And water.

  • by Theory of Everything (696787) on Wednesday September 29, 2010 @08:40PM (#33742284)

    I actually work quite closely with 2 of the authors of the paper that reports these results. Any questions? I'll try to respond to posts between now and 2 October.

    • Re: (Score:3, Interesting)

      by chebucto (992517)

      Can you explain, in layman's terms, how you determined the planet was tidally locked with its sun?

      • by Theory of Everything (696787) on Wednesday September 29, 2010 @11:06PM (#33743220)

        I believe they determined it as follows:

        The planet is close to its star.

        The planet has a fairly well known size.

        The gravitational force on the near vs. far side can be calculated based on the planet-star distance and the planet size.

        Guessing the planet is mostly rock (a very safe guess based on lots of planetary science information), we can guess how much frictional energy is lost in that differential stretching.

        Based on the elements observed in the star, we can estimate the age as billions of years old.

        The frictional forces would slow down the planet rotation much faster than billions of years. Thus, by now, it would be tidally locked.

        The key is that the planet is closer to its star than the Earth. For example, Mercury (which isn't even as close to the Sun as GJ581g is to its star) is in a 3:2 tidal lock between its orbit and rotation. The full 1:1 lock is expected for closer planets. This is the case for the Earth's Moon, which is why we always see the same side of the Moon. This tidal locking is extremely well established with the Earth's Moon.

    • by w0mprat (1317953) on Wednesday September 29, 2010 @10:54PM (#33743166)
      Aren't Red Dwarf stars often unstable and known as flare stars? This would be a problem for life in the Gliese system? Or is Gliese more stable being larger than most of these?

      Is there any meaningful insight into the balance of elements in the stellar system (from looking at the spectra of the star) that would help guess the composition of the rocky planets - would there be plenty of the right stuff for life? I ask because I read Gliese is 7-11 billion years old and older stars have less heavy elements, I'd guess that the system would not have the same abundance of metals and heavier elements.

      Does the spectra of a star give any clues to the abundance of water in the star system? At least upper and lower bounds?
      • by Theory of Everything (696787) on Wednesday September 29, 2010 @11:34PM (#33743368)

        Good point!

        There is some controversy here. GJ 581 doesn't seem to be to dramatically variable. But others are. The lead of SETI wrote a recent paper claiming M dwarfs are not so active as to prevent life or even advanced life. However, this was in response to papers claiming the opposite. It's uncertain, but it seems GJ 581 is stable enough for long enough periods that life can evolve. Even our Sun isn't super stable, yet life exists. Thus ice ages, the Maunder Minimum and Mini-Ice-Age, and the like.

        The spectrum of the star wouldn't necessarily tell us about the composition of planets. Some planet-star spectrum correlations have been seen as far as whether stars have planets, but these have not necessarily been tied to causation, and certainly not to composition of the planets. We would certainly need to calibrate any such tracer first, anyways.

        The composition-age relationship for stars that you mention has more to do with the generation of stars. Stars today are made out of the waste products from the exploded material from previous stars. That material is enriched by the nuclear processes from those previous stars, meaning they start with more heavy elements. The current generation includes stars today and those from at least as long ago as 10 billion years. Beyond that you start to get to the beginnings of the universe and earlier generations of stars. So no big changes are really expected here, and the phenomenon you cite isn't currently believed to be planet-related, but rather just evolution-of-the-universe related, a very different topic.

        I don't think anything about the spectra of the star could identify water at this level of precision. Planets are a billion times fainter than their stars. The spectra had signal-to-noise ratios of order 300:1, which is impressive enough, but nowhere close to enough to see features of the planet. (If Bill Gates, the man of $60 billion, woke up tomorrow with $60x300 = $18,000 to his name, he might need to be put on suicide watch. That is the level of change we are talking about.)

  • by Tumbleweed (3706) * on Wednesday September 29, 2010 @08:55PM (#33742416)

    I'm much more interested in the possibilities of exploring alternate Earths. Somewhere, I'm just SURE I'll find a world where everyone in the U.S. uses the evolved form of the Amiga, with Dvorak keyboards in Esperanto. And the metric system. I'm dying for a McDonalds Royale (hold the cheese and pickles), with a medium Dr. Pepper with pure cane sugar (no ice).

    Maybe the alternate world in Fringe will be a good start, only less fascist. I love the dirigibles and the NYC skyline.

  • Wow (Score:5, Insightful)

    by MyLongNickName (822545) on Wednesday September 29, 2010 @09:07PM (#33742502) Journal

    My what exciting times we live in. Just think... it has only been around 100 years since we realized the universe is organized into galaxies. Only a few hundred since we realized that the Earth is not the center of the universe. Sometimes it is hard to have faith in the future... but discoveries like this touch that small part of me that hasn't become jaded.

    • Re: (Score:3, Informative)

      by Newtonian_p (412461)

      "The Great Debate" occured in 1920 and it took a while after that to figure out that Heber Curtis was right. It's crazy that it took so long to develop the telescopes needed to find out there are other galaxies out there.

      And in less than 90 years since then, we now have the technology to take those Deep Field pictures showing tens of thousands of galaxies at a time when the Universe was 300 million years old.

  • What this isn't... (Score:5, Informative)

    by SETIGuy (33768) on Wednesday September 29, 2010 @09:22PM (#33742610) Homepage

    First, TFS is wrong. This planet is 3 to 5 times the mass of the Earth, not 30%.

    The article also won't tell you what is speculation and what they've actually seen. The planet was detected through radial velocity measurement of the star. That pretty much means the only thing that has been measured is the planetary mass times the sine of the inclination of its orbit relative to the sun-Gl581 line. Hence the large uncertainty.

    When they talk about atmospheres they are speculating. There is no way to tell if this planet has an atmosphere, although the large mass helps the case. There's no way to tell if the planet is covered in an 100 mile deep ocean or if it is entirely dry other than by speculating based upon the composition of the host star. With no eclipses and a small planet to star distance it's going to be a while before we know for sure about either.

    When they are talking about tidal locking they are also speculating. While the planet would almost certainly be tidally locked to the star if it were the only planet in the system, it could exist in an orbital resonance with another planet that throws off the tidal locking, or it could have a large moon in close orbit, which would also do the job.

    I also haven't looked to see which version of the habitable zone definition they are using. I would suspect the run-away greenhouse to ice-line version.

  • by physicsdot (530505) on Wednesday September 29, 2010 @10:11PM (#33742916)
    20 light years is *about* 1.25 million AU. Voyager is 113 AU from the sun, in under 4 years it will be 125 AU from the sun. If we pretended Voyager 1 was heading the in right direction it would be 1/10000 of the way there. Or if we imagined that the planet was 10 meters away, Voyager has travelled 1mm of the way there. About 350000 AD, it would arrive!

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