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Space Earth

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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  • 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 2.0.
  • Re:Better leave now (Score:5, Interesting)

    by Em Adespoton ( 792954 ) <> on Thursday April 17, 2014 @02:52PM (#46781629) Homepage Journal

    I know there has to be a book about that, but it's slipped my mind.

    The whole thing of "first wave" colonists who spend generations getting there, and when they do... they find that the third wave colonists have been there for a few generations already, and all the planets habitable by them and their archaic technology are already taken.

  • 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.

  • 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 barlevg ( 2111272 ) on Thursday April 17, 2014 @03:43PM (#46782147)

    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 method would only take about two years for the passenger.

    Of course, you need a way to fuel a ship that's accelerating/decelerating at one gee for two years, but that's just an engineering problem.

  • 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:Air pressure? (Score:3, Interesting)

    by kwiecmmm ( 1527631 ) on Thursday April 17, 2014 @03:55PM (#46782273)

    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 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.

  • 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.
  • Re:Better leave now (Score:4, Interesting)

    by allcoolnameswheretak ( 1102727 ) on Thursday April 17, 2014 @05:10PM (#46782857)

    Then there is also "The Forever War", where, among other things, fleets of spaceships travel to a war zone only to find out the war has long ended once they arrive there.

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