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Space Science

Scientists Discover Exoplanet Less Than Twice the Mass of Earth 201

Posted by Soulskill
from the it's-so-small dept.
Snowblindeye writes with this excerpt from the European Southern Observatory: "Well-known exoplanet researcher Michel Mayor today announced the discovery of the lightest exoplanet found so far. The planet, 'e,' in the famous system Gliese 581, is only about twice the mass of Earth. The team also refined the orbit of the planet Gliese 581 d, first discovered in 2007, placing it well within the habitable zone, where liquid water oceans could exist. Planet Gliese 581 e orbits its host star — located only 20.5 light-years away in the constellation Libra ('the Scales') — in just 3.15 days. 'With only 1.9 Earth-masses, it is the least massive exoplanet ever detected and is, very likely, a rocky planet,' says co-author Xavier Bonfils from Grenoble Observatory. Being so close to its host star, the planet is not in the habitable zone. But another planet in this system appears to be. ... The planet furthest out, Gliese 581 d, orbits its host star in 66.8 days. 'Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star,' says team member Stephane Udry. The new observations have revealed that this planet is in the habitable zone, where liquid water could exist. '"d" could even be covered by a large and deep ocean — it is the first serious "water world" candidate,' continued Udry."
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Scientists Discover Exoplanet Less Than Twice the Mass of Earth

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  • Astronomy (Score:5, Interesting)

    by Reorix (1184073) on Wednesday April 22, 2009 @12:19PM (#27675685) Homepage
    I always hear about these sorts of discoveries, of new planets more and more similar to earth, but having almost no astronomy background, I have no idea how significant they are.

    How much do we really know about these planets, and how much is guessing? How close are these planets, really, to earth?
    • by olsmeister (1488789) on Wednesday April 22, 2009 @12:30PM (#27675807)
      It's 20 (or so) light years from Earth. According to this [theregister.co.uk] article, we've probably already pissed off any inhabitants...
      • by jollyreaper (513215) on Wednesday April 22, 2009 @01:47PM (#27676795)

        It's 20 (or so) light years from Earth. According to this [theregister.co.uk] article, we've probably already pissed off any inhabitants...

        We still have what, ten years left to invent an FTL drive and get there to preemptively apologize for reality television, right?

        • We still have what, ten years left to invent an FTL drive and get there to preemptively apologize for reality television, right?

          Faster than light merely means... Faster than light. c + 1 cm/second would count, but would get us there mere microseconds before the announcement that we had started the trip. Leaving now, we would need to go at >2c.

      • Re: (Score:3, Funny)

        by Rary (566291)

        It's 20 (or so) light years from Earth.

        To put that in a context that ordinary nerds without astronomy backgrounds can understand, it's 37,842,113,600,000,000,000,000,000 beard seconds [wikipedia.org] from Earth.

    • by SalaSSin (1414849) on Wednesday April 22, 2009 @12:33PM (#27675861) Homepage Journal
      If you would like to know more, download Celestia [shatters.net], an open source project to cruise around the universe in 3D.
      Just select "go to object" and type in "gliese 581", you'll get the orbits of the different planets already found too.

      The neat thing is, you can just "cruise" around, speed up time to see how stellar objects move, and so on... Quite cool :-)
    • Re:Astronomy (Score:5, Informative)

      by confused one (671304) on Wednesday April 22, 2009 @01:01PM (#27676243)

      The significance is that our methodology is improving. Only in the past decade or so have we been able to identify stars with possible planets. Only in the past year or two have we been able to directly image a planet (or separate it's image from the parent star). What we know of the planets is based on how close it's orbit is to the star, it's estimated mass, and in a few recent cases, based on limited spectroscopic information.

      Now that Kepler's working, over the next 2-3 years we should have a flood of these reports. (keep in mind Kepler's only imaging a 10 x 10 degree patch of sky) In the next decade we will develop the means to directly image a nearby terrestrial sized planet.

      All of the planets imaged so far are relatively close, on a galactic scale. A few 10's of light years. There's more than enough information out there to explain how far that is from a human perspective. Let's just say, that based on current technology, none of our great-grand children will get an up close look. (although I suppose we could do a fly by of something like the Gliese 581 system, with a probe, in the next 3-4 generations, if we tried hard enough.

      • by jez9999 (618189)

        If we can see planets a vast distance away so well, why are we having to send New Horizons all the way to Pluto to get a good piccie of it? Can't we point Kepler at it or something?

    • Re: (Score:3, Insightful)

      by Kjella (173770)

      I always hear about these sorts of discoveries, of new planets more and more similar to earth, but having almost no astronomy background, I have no idea how significant they are.

      Consider it a bit like breaking a world record, "closest to Earth" is a big title but ultimately you only need to beat the old record by an inch. The answer I'd say is "much, much closer than anything we've observed in the history of mankind and still very, very far away". There's so many variables you could tweak about size, distance from star, temperature, rotation time, composition, magnetic field, atmosphere, jupiter-type asteroid shields and whatnot. We're very far from saying whether anything we find

    • by arminw (717974)

      ...How close are these planets, really, to earth?...

      In order to have intelligent life, not only must the planet itself be similar to Earth in all respects, but the star it orbits must be very similar to our Sun. In this case, the star is too cold to emit the proper spectrum of light to use for knitting together atoms of carbon, hydrogen and oxygen, such as occurs here on Earth by the process of photosynthesis in green plants. This means that this star and others like it can be safely scratched from a list o

      • by w0mprat (1317953)

        In order to have intelligent life, not only must the planet itself be similar to Earth in all respects, but the star it orbits must be very similar to our Sun.

        No. We don't know that. We can't even begin to assign odds on what we might find when we turn over a rock on the surface of another world. With our sample size of 1, Earth, we have next to no data to support much to do with extraterrestrial life let alone any basis to declare where intelligent life can and cannot exist.

        Oceans under Europa and other such worlds may harbor life, and the possibility of complex life is valid, therefore the possibility of intelligent (at some level) life can't be discounted.

  • by squoozer (730327) on Wednesday April 22, 2009 @12:20PM (#27675695)

    This is very interesting but no where near as exciting as finding another Earth like planet. I suppose we will have to wait for the next generation of telescopes before we find it though.

    What is a little surprising though is how many planetary systems we have found that are very different to our own. I can't believe ours is unique but perhaps it's quite rare.

    • by Chris Burke (6130) on Wednesday April 22, 2009 @12:35PM (#27675901) Homepage

      This is very interesting but no where near as exciting as finding another Earth like planet. I suppose we will have to wait for the next generation of telescopes before we find it though.

      Well the 'e' planet is somewhat earth-like in mass and possibly earth-like in composition. It's not in the habitable zone for the star, but the closer a planet is to the star the easier it is to detect, and this exoplanet is at the very edge of our ability to detect (thus why this is news -- smallest exoplanet ever found). So you're right, we'll have to wait for technology to advance to find earth-sized rocky planets in the habitable zone (especially of non-dwarf stars).

      What is a little surprising though is how many planetary systems we have found that are very different to our own. I can't believe ours is unique but perhaps it's quite rare.

      I'm not sure anything we've found suggests that our type of solar system is rare. The limitations of our detection method by and large assures we'd find systems different from our own first. Astrophysicists might not have expected to find gas giants very close in to stars, but if they exist, we were going to find those first. The two main things that seem to have changed to me are that 1) we've gone from having nothing but our own solar system as an example and thus assuming ours was the model for all of them, to have many more examples showing different types and 2) we've learned that solar systems seem to be pretty common.

      If we get to the point where detecting a solar system like ours would be simple, and despite finding thousands of others we don't find any like ours, then maybe that points to rarity. Right now though I doubt we're anywhere near being able to say that.

      • Re: (Score:3, Informative)

        by DragonWriter (970822)

        I'm not sure anything we've found suggests that our type of solar system is rare. The limitations of our detection method by and large assures we'd find systems different from our own first. Astrophysicists might not have expected to find gas giants very close in to stars, but if they exist, we were going to find those first.

        To elaborate on that (you covered the distance part, yourself), the main factors is detecting exoplanets right now are (1) its easier to detect bigger exoplanets, and (2) its easier to

      • Re: (Score:3, Interesting)

        by zacronos (937891)
        There's something I wonder about which sounds like it would be enlightening to GP as well:

        If we were using our current detection technology to examine a solar system that has a planet exactly like earth, orbiting a star exactly like our sun, with the same orbital period, etc... how close would the solar system need to be for us to recognize those features? Could we recognize an earth-sized planet orbiting a star in the habitable zone if it were 20 light-years away? What about 30 light-years? How clos
    • Re: (Score:3, Informative)

      by Kell Bengal (711123)
      Maybe our type of planet is just difficult to find because it's so (relatively) small?
    • Re: (Score:3, Informative)

      > This is very interesting but no where near as exciting as finding another Earth like planet.
      Planet Gliese 581 e is an earth-like planet. It's just not in an earth-like orbit.

    • I can't believe ours is unique but perhaps it's quite rare.

      Every star and planet is unique. They weren't made from an assembly line y'know!

      And don't forget our form of life is equally unique, so it's a real needle-in-the-haystack situation. Kepler can search 10 x 10 degrees at a time, but with limited depth per scan, i.e. it has to change focus for objects 80 light-years away compared to objects 20 light-years away.

      Then there's the inconvenient fact that communications take so long between such distant

  • Planets and moons (Score:4, Interesting)

    by nizo (81281) * on Wednesday April 22, 2009 @12:22PM (#27675719) Homepage Journal

    Gliese 581 d is probably too massive to be made only of rocky material...

    Even if it isn't habitable, it might still be large enough to have a habitable moon perhaps?

  • Good news (Score:5, Funny)

    by KingPin27 (1290730) on Wednesday April 22, 2009 @12:23PM (#27675725)
    "could even be covered by a large and deep ocean â" it is the first serious "water world" candidate" .. Good.. I wonder if we can export Kevin Costner.
  • by Chris Burke (6130) on Wednesday April 22, 2009 @12:23PM (#27675727) Homepage

    Water worlds always have the crappiest minerals. Oh look more alkalines. Yay. It won't be worth spending the fuel to land on Gliese 581 d, much less the cargo hold space. Gliese 581 e might have iron and other metals, but being so close to the star it probably has major hot spots. So that's probably not worth landing on either until we meet the Melnorme and buy some tech off them.

    Oh well. Eliminating planets to explore is good too. There's a lot of stars in the sky, you know, and only so much time to explore them before the UrQuan return.

  • Only 20 years away? So, by the time global warming gets catastrophic, we can already seed another world.

    Meh.

    As in Moonraker, we send the sexy geniuses first, right? Or do we send the Telephone Sanitizers and hairdressers, like in HHGG?

    • Re: (Score:2, Informative)

      Yeah, if we were able to travel at the speed of light.

      • By who's observation?

        Don't the actual passengers get there in a few hours, their own time, or something crazy like that?
        • by nizo (81281) *

          By someone standing on either Earth or the destination planet? Though it just occurred to me, I find it cool that to the photons from my lcd monitors I am traveling towards them at the speed of light.

    • by Chris Burke (6130) on Wednesday April 22, 2009 @12:38PM (#27675951) Homepage

      As in Moonraker, we send the sexy geniuses first, right? Or do we send the Telephone Sanitizers and hairdressers, like in HHGG?

      Well according to the travel register, you're booked on the first flight! Take that however you want.

  • Did anyone else glance at Gliese and read that as uncomfortably close to Goatse.cx?

    By the way, off topic, as it is, how does one prevent from being fooled by tinyurl links to goatse.cx?

  • by Morgaine (4316) on Wednesday April 22, 2009 @12:54PM (#27676149)

    The science of extra-solar planet detection is very interesting, but speculation about surface conditions that might exist doesn't reflect the science at all, it's just fodder for the media and bloggers.

    The only things we know are extremely rough estimates of orbital parameters and mass, although the host star is well characterised. The speculation is conjuring up quite specific images in people's minds, and while fun, they're not justified. It's leading people without an astronomy background astray.

    • by 0xdeadbeef (28836)

      "'The holy grail of current exoplanet research is the detection of a rocky, Earth-like planet in the 'habitable zone' -- a region around the host star with the right conditions for water to be liquid on a planet's surface', says Michel Mayor from the Geneva Observatory, who led the European team to this stunning breakthrough."

      Indeed. Who do these scientists think they are, making their work sound interesting?

  • What class? (Score:2, Interesting)

    by amliebsch (724858)
    So, is it an M-Class planet or not?
  • ... it's a Beowulf Cluster.

    What, you were maybe expecting something else?

  • Soulskill writes:
    "...it is the first serious "water world" candidate,' continued Udry."

    Excellent.

  • The orbital period of these exoplanets make Mercury's 88 day loop seem positively sluggish by comparison. The rest of the planets in our system have much longer orbital periods - Earth's is a bit over four times mercury's - to say nothing of the geologic sloth of the outer planets.

    That said, from what I know about gravitational microlensing (very little, admittedly), it makes sense that our existing telescopes are picking up a lot of "high speed" planets, and that it's going to take a long time (both in ra

    • Re: (Score:2, Interesting)

      by Mendokusei (916318)

      it's going to take a long time (both in ramping up the tech and in tasking the scope to just sit there and stare at a star, waiting for something to blip by) for the "earth-sized rock in the habitable zone with an earth-length orbital period!" announcements to start rolling in.

      I wouldn't think that an "earth-length" orbital period is all that important to determining if a planet can support life or not. Remember, the type of the star it orbits determines where and how large the habitable zone will be, so if

  • Planet Gliese 581 e orbits its host star -- located only 20.5 light-years away [...] in just 3.15 days.

    The planet orbits a star 20.5ly away from it in just over 3 days? I figured if superluminal travel existed it would involve quarks or virtual particles, not entire planets! Not to mention I'm surprised that 20.5ly is apparently a small distance to orbit from ("only 20.5 light years away").

  • Given that they're 20 years away, IN THE MILLENIUM FALCON, is it even interesting if they are habitable or not? I can picture it now, we use a radio telescope to send "Hello" and wait 40 years to get back "A/S/L ?".

  • ...the definition of "earth-sized" planet shrinks.
  • It is interesting the reason we aren't seeing more planets closer to earth size is simply the limits of the sensitivity of our observations. This is interesting, the star being red dwarf, such stars outnumber ones like our sun 10 to 1 in this galaxy, the Gilese system shows these stars could be very planet friendly.
  • I'm building an Ark and plan to retire to this paradise planet. The current crime rate is 0% and there are no taxes at all.
    Invest now in this limited opportunity and don't be too late to take advantage of this exclusive offer.
    Just reply to this thread with your bank routing number and account number along with the amount you wish to invest.

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