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Kepler-186f: Most 'Earth-Like' Alien World Discovered 239

astroengine (1577233) writes "About 500 light-years away in the constellation Cygnus lives a star, which, though smaller and redder than the sun, has a planet that may look awfully familiar. With a diameter just 10 percent bigger than Earth's, the newly found world is the first of its size found basking in the benign temperature region around a parent star where water, if it exists, could pool in liquid form (abstract). Scientists on the hunt for Earth's twin are focused on worlds that could support liquid surface water, which may be necessary to brew the chemistry of life. "Kepler-186f is significant because it is the first exoplanet that is the same temperature and the same size (well, ALMOST!) as the Earth," David Charbonneau, with the Harvard-Smithsonian Center for Astrophysics, wrote in an email to Discovery News. "Previously, the exoplanet most like Earth was Kepler-62f, but Kepler-186f is significantly smaller. Now we can point to a star and say, 'There lies an Earth-like planet.'""
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Kepler-186f: Most 'Earth-Like' Alien World Discovered

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  • by pablo_max ( 626328 ) on Thursday April 17, 2014 @02:32PM (#46781425)

    If I do, I could be there in what, 25k years..round about?

    After all, Mericans are always saying to me "if ya don't like it, git'out".

    • by gmuslera ( 3436 )

      Even for going small distances like to Mars space radiation is a big problem. The fastest probes that we send out (that don't have to carry a complete ecosystem for us to live) could need more than 25k years just to get to the closest star system, at more than 100 times less distance than that planet. Probably no human will ever reach another solar system, so visiting there is badly out of the question.

      Whats left? Contacting with a possible civilization there? Our planet has been with this size and in thi

      • by mark-t ( 151149 )

        Probably no human will ever reach another solar system

        I think that depends on whether or not you think that creatures who have human beings as evolutionary ancestors would count as human.

      • Re:Better leave now (Score:4, Informative)

        by Penguinisto ( 415985 ) on Thursday April 17, 2014 @05:55PM (#46783225) Journal

        I suspect things work a bit more linearly than you might surmise. Maybe I just read your post wrong, but let me re-word it to see if I got it right, with a few changes:

        Right now, we (as a human civilization) have pumped out radio signals that currently are racing out past the 100+ light year mark. This is stuff we sent long ago (e.g. Titanic's SOS call has reached the 102-light-year-mark, other early Marconi radio broadcasts in Morse code, stuff like that.)

        The initial contact is the bitch - you send something out to a planet 50 ly away, hope someone is there and is capable of listening at that moment, along the frequency band you sent, has his antenna pointed at the same vector from which your signal is originating, has sufficient technology and skill to discern it as a intelligent/sentient message created intentionally. Oh, and you'd better hope something in-between doesn't obliterate the signal on its way there, and that it was powerful enough to not be diffused too much.

        Meanwhile, your alien recipient not only has to receive it, but he needs to be capable of sending something in return. If he can decode what you sent and then send a suitable reply - bonus! If he sends something with the same pattern back, okay.

        Now we get to wait another 50 years before the reply gets back here, we still have to be around as a civilization (with the right equipment!) to hear it, have someone interested in listening for it (what, 100 years after his grandpappy sent the original signal?), and again, hope the alien dude didn't decide that maybe a different and random (to you) frequency band would have been better to send the reply with... and toss in the same hazards experienced when sending the original request signal.

        (...and you thought postal service was slow...)

    • Actually, at 1g acceleration it would take about 11 years to reach the mid-point and another 11 to decelerate back to a resting frame rate. So 22 years to the traveler which is certainly doable. Of course to us on earth this would be over 500 years into the future due to time dilation. Also, I'm assuming we'd solve the problem of finding the enormous amounts of energy required for 22years of uninterrupted thrust, the spacecraft could operate flawlessly for that amount of time, and that the planet isn't movi

      • If you can get there in 11 years, you would have to be travelling at 45 times the speed of light on average. Since you can't accelerate to, or above the speed of light, you're either assuming that you started above the speed of light, or your maths is really badly wrong.

        • Re:Better leave now (Score:4, Informative)

          by arth1 ( 260657 ) on Thursday April 17, 2014 @09:13PM (#46784589) Homepage Journal

          Sorry, but time is not an absolute clock that ticks the same everywhere. Time is a local phenomenon, and only a local phenomenon. We all live in separate time frames.

          If you accelerate to 99% of the speed of light, the Lorenz factor is a little over 7, which means that for an outside observer counting one year on the clock, you will only have experienced 51 days.
          As your speed creeps closer and closer to c, the time dilation increases. If you could reach 99.999% of c, the Lorenz factor would be 223. For an outside observer watching you travel 100 light years from A to B, 100 years would pass. But for you, less than 5.5 months would have passed.

          If you could maintain a 1g acceleration indefinitely, you could travel to another galaxy and back within a human lifetime. It's not feasible, though, as you require more and more energy to accelerate the faster you go, and as you approach c, you approach needing an infinite amount of energy for an infinitesimally small boost in speed.

    • by RichMan ( 8097 )

      No report of a Macdonalds franchise yet.

      • Re: (Score:3, Interesting)

        by Teresita ( 982888 )
        A world in the "habitable zone" of a class M dwarf star is only a few million miles away, orbiting in a matter of a few days. This means the planet will have a tidal lock, much like the Moon does with respect to the Earth. And that means the night will never end on one side of the world. And that, in turn, will make the dark side so cold the air will precipitate out as snow. Then the atmosphere will equalize, and snow again. Lather, rinse, repeat. Ribbon worlds are airless worlds. Forget about Earth
        • by arielCo ( 995647 )

          It appears you missed a (silly) reference there: []

        • by amck ( 34780 ) on Thursday April 17, 2014 @02:57PM (#46781665) Homepage


          There have been several studies of tidally-locked planets around M-dwarfs which refute this.
          Simulations of the Atmospheres of Synchronously Rotating Terrestrial Planets Orbiting M Dwarfs: Conditions for Atmospheric Collapse and the Implications for Habitability, M. M. Joshi, R. M. Haberle, and R. T. Reynolds , Icarus (1997)
          A Reappraisal of The Habitability of Planets around M Dwarf Stars, Tarter et al. (2007), Astrobiology,

          Basically atmosphere and ocean circulation transfer the heat, and you get a relatively habitable earthlike environment.

      • but there IS a Starbucks

    • by mk1004 ( 2488060 )
      It's an alien planet! Is there air! You don't know!
    • by mrego ( 912393 )
      "A planet circling that far left star..." City on the Edge of Forever
    • Who cares, its finally an interesting enough target for us to actually think about building an interstellar probe. The sooner we launch one, the sooner our descendants get to hear back from it.
      • by Immerman ( 2627577 ) on Thursday April 17, 2014 @04:53PM (#46782717)

        >The sooner we launch one, the sooner our descendants get to hear back from it.

        Not necessarily. Or more precisely by the time they hear back from it the information will likely be completely redundant.

        At present all our mature propulsion technology is very much focused on planetary usage. Rocketry is the only one at all suitable to operating in space, and it's *horribly* inefficient in terms of specific impulse, which will be *the* deciding factor for interstellar travel. Ion drives show immense promise, already completely trouncing chemical rocketry in terms of specific impulse, but it's a technology very much in its infancy and the absolute thrust current engines can produce is miniscule, useful for little more than station-keeping and lining up gravitational slingshot maneuvers. If we launched an interstellar probe with today's technology then it's quite likely that a second probe launched 50-100 years from now would be able to make several round trips before today's probe ever got anywhere close to the target. For a mission whose expected payoff is centuries away that sort of thing is well worth considering. Much like Voyager making its pokey way out of the solar system, the value of an interstellar probe built on current-gen technology would be primarily in learning about the beginning of the path, not the destination. And unless there's some completely unexpected navigation hazard in the gulf between stars there's unlikely to be much to learn worth the cost of the probe.

        Now what might be an interesting mission with current or near-term technology is a gravitational-lens telescope - rather than sending a probe towards Kepler-186f we send a telescope "eyepiece" in the opposite direction, and when it reaches a distance of only about 700AU (0.011 light years, ~10x Voyager 1's current distance) away from the sun we could start to use the sun's gravitational field as an immense lens in a telescope so powerful we could count the pebbles on 186f's hypothetical beaches. Maybe even individual grains of sand. Not to mention everything else we might see in that general direction. The downside to such a telescope is that it's extremely difficult to substantially change the target. With a telescope 700AU long even a few degrees of change requires moving your eyepiece across a distance rivaling Pluto's orbit. Still, with a clever flight plan we could get immensely detail information about dozens or hundreds of other star systems as our eyepiece slowly swept out a few degrees of motion. The only real question is, is 186f really interesting enough to be the first target? I would imagine looking toward the galactic core would offer far more interesting things to see.

        • That is a really cool idea. I can honestly say i'd never heard anything like it before, thank you for making me smarter today.
  • Shh (Score:5, Funny)

    by gatkinso ( 15975 ) on Thursday April 17, 2014 @02:36PM (#46781469)

    If we are quiet, maybe we'll get lucky and they won't notice us....

    • Re:Shh (Score:4, Interesting)

      by CrimsonAvenger ( 580665 ) on Thursday April 17, 2014 @02:58PM (#46781675)

      500 ly away...

      Sounds like we have 350-400 years before they start hearing our radio noise. After that, we might need to worry....

      • by Anonymous Coward on Thursday April 17, 2014 @03:24PM (#46781945)

        If they are advanced enough to travel here then they've had their own version of the Kepler telescope for 500 years and have known at the minimum that Earth has liquid water, oxygen, and chlorophyll (I think that can be picked up used spectroscopy). Basically anyone advanced civilization nearby probably has known about Earth as a life-bearning world long before humans came along.

        Just a cool thought to counter the idea that we're hidden until someone detects radio.

        • by gatkinso ( 15975 )

          Well, I know the pond is there... but are there fish in it? I don't know until I see one jump.

          • Well, if life-bearing worlds are rare enough to be interesting then if our planet was noticed there's a fair chance that aliens would have at least put a gravitational-lens telescope around their star focused on us, if only as a study in xenobiology. In which case they could quite possibly have been counting our ancestor's lice hundreds of thousands of years ago.

        • by gman003 ( 1693318 ) on Thursday April 17, 2014 @05:49PM (#46783165)

          have known at the minimum that Earth has liquid water, oxygen, and chlorophyll

          Chlorophyll doesn't need to be detected - the presence of elemental oxygen alone is evidence of life, as it is too reactive to remain elemental unless some reaction is replenishing it, and as far as we know the only such reactions are biological in nature.

        • If they are advanced enough to travel here then they've had their own version of the Kepler telescope for 500 years

          It does not follow.

  • Is figure out a way to get there within a human lifespan, with a couple caveats:

    1. females need to get there in an early enough age to reproduce and start a colony.

    2. figure out a way to get there before we destroy our own planet.
    • No, it would be OK to send a generation ship, where people live their lifespans on board raising their children. Assuming we could build something that lasts long enough without a BSOD.
      • by cusco ( 717999 )

        Why does almost everyone seem to assume that once the ship is launched the inhabitants won't be maintaining, repairing and improving it along the way? I've never understood that.

        • Oh, of course, their full-time job - in fact, their *lives* - will be dedicated to maintaining, repairing, and improving the ship, not to mention growing their food (easiest way to recycle). We already have some of that technology - I just read an article in this week's New Yorker about people working on a US Navy air craft carrier, with many people in tight space, no privacy, hazards everywhere, etc. But even a carrier expects supplies and spare parts delivered in port, or in emergency by air. Submarine
        • see also "The Long Way Home", Fred Saberhagen []
        • "Starlost", a badly-done early-1970s TV show that wasted a promising premise (by Harlan Ellison): The multiple bio-domes of a generation ship have been sealed off from each other for hundreds of years after an accident damaged the ship's bridge. The people in each have long forgotten that they are on a ship at all; they only know their little world, like medieval peasants. A handful of people try to escape their own little community and discover that there are other humans - and, after contacting the shi
          • by arth1 ( 260657 )

            Which in turn was undoubtedly inspired by Aniara, the 1956 Sci-Fi poem by Harry Martinson.

    • Re: (Score:3, Interesting)

      by barlevg ( 2111272 )

      I worked out this whole interstellar travel problem years ago. Also solves the problem of the negative effects of zero gee in space.

      All you need is to have your ship accelerate at a constant rate of one gee, do that for half the trip, then turn the ship around and decelerate at the same speed until you get to your final destination.

      The acceleration solves all your artificial gravity woes, and relativity solves all your lifespan worries--by my calculations, a trip to anywhere in the universe using this metho

      • by QuantumPion ( 805098 ) on Thursday April 17, 2014 @04:35PM (#46782571)

        An engineering problem in the sense that there is not enough matter in the universe to accelerate a spacecraft at 1 g for 2 years using any currently plausible propulsion method.

        • by nickersonm ( 1646933 ) on Thursday April 17, 2014 @04:58PM (#46782765)
          Interesting fact: at ~0.7c, the kinetic energy is equal to the rest mass of the ship. So if you have a photon drive running off of a perfectly efficient total conversion engine, you'll have fed more than half your ship to the converter by then.
        • (Not trolling here but curious)


          So I get that when you get closer to c you need exponentially more energy to accelerate.

          But what if we just got to 0.25c. That's only 2,000 years to destination, and totally doable I would guess

        • Light sales (x-ray). A 10KeV X-ray laser (about 0.1 nanometer wavelength) with a 10 kilometer final focus optic has a divergence of 1e-14, will be 10 kilometers wide at 1e18 Meters or about a light-year. the final lens could probably be a 10km zone plate out by the orbit of Neptune. The 10KeV X-rays will be stopped in a few microns of (tungsten) sail material.

          The sail will weigh 10s of tons. Need a laser power around a few to tens of terawatts to get around 1G.

          All depends on what you consider "plausibl

        • Are fusion ramjets that magnetically scoop interstellar gas & dust implausible? Curse Larry Niven for making a mockery of my childhood dreams!
          • They are really hard. Hard to imagine a magnet that has enough strength to weight to collect enough hydrogen, and much of the hydrogen isn't ionized anyway. Then you need to be pretty efficient or you generate so much drag collecting the hydrogen that you don't gain from fusing it. Then there is the problem that it is almost all H1, not deuterium, and H1 fuses incredibly slowly, so its hard to imagine the reactor.

            No crazier than other ideas, but really really hard.

            All this is a bit silly. The equivalent

  • had the Monolith reporting to someone/something about 450 ly distant. It had reported how bad humans behaved, and was therefore ordered to destroy them. The messages took a combined 900+ years, so it didn't receive orders until 3001. What a coincidence. Or maybe I remember all that wrong.
    • That's what I remember, too. Although that only applies to the "chronology" of 3001. Clarke has explicitly stated that 2001, 2010, 2061 and 3001 all exist in separate but similar universes (read: he was too lazy to worry about continuity issues across novels).
  • You know what makes a planet Earth-like? Having life on it. Not theoretically maybe being able to support life, but actually doing so.

    • Earth-like IMO means being in the habitable zone w/ liquid water, about Earth-sized, rock world, preferably with molten core and magnetic field. Life is optional.

      Europa and Encelaedas [sic] might by "earthlike" by your definition.

    • by mark-t ( 151149 )
      Why do you figure that actually having life should be a criteria for being earth-like? Like does not have to mean "exactly the same as".
      • Well, because when one is making up arbitrary things, they might as well be remotely interesting, and based on my whims.

        Seriously though, that it is teeming with life is the *one* thing that sets Earth apart from the other planets we know so far. That's kind of the whole big deal about it. If this criterion doesn't matter, then why care about "Earth-like" at all? What about the Jupiter-like and Neptune-like and Venus-like planets being discovered all the time?

        Oh wait, that would be silly, because we already

        • by mark-t ( 151149 )
          Knowing its out there somewhere and actually finding something that fits the criteria are two different things.
  • "Now we can point to a star and say, 'There lies an Earth-like planet."

    No, now we can point to yet another object in the sky and say "there lies another planet we haven't even remotely figured out how to get to yet."

    I just love how we wax poetic about earth-like planets as if we can get there. Or even have a hint as to how to get there beyond theories Einstein wrote 100 years ago.

    Seriously. We can't even figure out how to travel ONE light year, and we're getting all excited about one that's "only" 500 light years away.

    • True, but if there were life there then we could peek in their windows easily enough - it's only lack of sufficiently interesting targets that keeps us from building a gravitational telescopes around the sun. And if they were sufficiently technologically advanced we could potentially communicate. The lag would be horrible, but cultural and/or technological exchange could be mutually beneficial.

  • I believe this planet will be like Venus, a rocky surface, but a CO2 atmosphere that makes it at least 300 degrees Celsius on the surface.

  • Air pressure? (Score:5, Interesting)

    by scorp1us ( 235526 ) on Thursday April 17, 2014 @03:46PM (#46782181) Journal

    How much of this "habitable zone" factors in water's ability to be liquid to to pressure? Too thin it vaporizes (Mars). Too much, it vaporizes (Venus). Merely being the right temperature isn't enough.

    Also, having a magnetic pole strong enough to shield it from the solar wind, so what does wind up in the atmosphere doesn't wind up in space.

    • Re: (Score:3, Interesting)

      by kwiecmmm ( 1527631 )

      There is also the age of the solar system to worry about. If it is in its early years there could be constant planetary bombardment going on.

      If it is in its later life the planet's core could have shut down, leaving no shield.

      • by Kjella ( 173770 )

        Which is why this is a never-ending competition, one thing is size but what about mass/gravity? Does it have a magnetic field? Does it have a Jupiter to clear the solar system of debris? Does it have a moon to produce tidal forces? Still, we know there's some slack in that life is almost everywhere on this planet from Sahara to the Arctic.

    • >Too much, it vaporizes (Venus)

      No, as you increase the pressure the boiling point also increases. The reason water only exists as a vapor on Venus is not because of the air pressure of 90atm at the surface - that's equivalent to being only ~900m underwater, while the average ocean depth is about 4300m.

      Instead it's because Venus is insanely hot thanks to the greenhouse effect of that thick CO2 atmosphere, which makes it far hotter than Mercury despite being much further from the sun.

  • We could send radio signals that far, with the big dish at Arecibo. If they have intelligence, and radio, we can communicate with a 1000-year round trip time. Maybe we should transmit some of the proposed canned messages to other civilizations every month or so.

    If there is other intelligent life out there, it looks like they're a very long way away. Too far to talk to round trip, even at light speed. None of the known extra-solar planets within a few light years look promising.

    • by mark-t ( 151149 )

      Actually, at near light speed, time slows down, so a person who embarks on a journey in a spaceship capable of moving near enough to the speed of light could conceivably reach a destination many hundreds or even thousands of light years away in their own lifetime.

      Of course, everyone that they left behind and ever knew will be long gone.

    • Extrasolar planet hunting is... spotty at best.

      If we actually sent a spaceship into a Jupiter sized orbit of another star, it would still take awhile to spot all the inner planets.

    • The transmission power necessary to stand out against the broad-spectrum radio noise generated by our sun would likely be truly staggering. There is some question as to whether even our most powerful military radar signals could realistically be detected from as close as Alpha Centauri. Not to mention the small but real danger in announcing our existence to a completely unknown alien species. Why not build a gravitational telescope first and peek in their windows? We could at least see what they were li

    • Some human organizations have survived ~1000 years, its taken ~500 years to finish some cathedrals, so the time scale isn't completely unreasonable. OTOH, I don't think advertising our presence is the best idea.

Would you people stop playing these stupid games?!?!?!!!!