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Thread: Discovery of first habitable exoplanet? Or rather not.

  1. #1 Discovery of first habitable exoplanet? Or rather not. 
    Moderator Moderator Dishmaster's Avatar
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    NASA came up with another press release block buster claiming to have found the first habitable exoplanet. Since then, this news is making its way all over the web, e.g. on Space.com.

    After reading most of it critically, one can say that one should be very careful! There are phrases used like:
    If confirmed, the exoplanet, named Gliese 581g, would be the first Earth-like world ...
    It really is monumental if you accept this as the first Earth-like planet ever found in the star's habitable zone, ... said Seager, who was not directly involved in the discovery.
    Jeez!

    And even stranger:
    Just as Mercury is locked facing the sun, the planet is tidally locked to its star, so that one side basks in perpetual daylight, while the other side remains in darkness. This locked configuration helps to stabilize the planet's surface climate, Vogt said.
    I doubt that this is a well founded statement.


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    Administrator KALSTER's Avatar
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    Vogt even said that the chance is 100% that it has life. :?

    Still a great find though. The planet has three times Earth's mass and is only slightly more voluminous, so it will probably have quite a different atmosphere than Earth's, if I am not mistaken?


    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
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    Interesting find. But guys, as scientists, we need to sell our profession to people who don't care for it. So, blockbuster headline: NASA FINDS LIFE, seems to be better than NASA FINDS POSSIBLY HABITABLE EXOPLANET 20 LIGHT YEARS AWAY.

    Its the nature of the beast, if science doesn't do this, then Lady Gaga's new costume takes more of the coverage. Simple.
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    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by KALSTER
    Vogt even said that the chance is 100% that it has life. :?

    Still a great find though. The planet has three times Earth's mass and is only slightly more voluminous, so it will probably have quite a different atmosphere than Earth's, if I am not mistaken?
    Not sure they have a handle on the planet's radius do they? And unlikely they will unless they can directly image or observe a transit. Forgive me if I am well outside my understanding but the atmosphere will depend a lot on the radius, since the radius and the known mass will tell us the surface gravity, which currently we can't estimate. More gravity will tend to mean thicker atmosphere, all of which may well be irrelevant if that atmosphere did not have good heat distribution properties. If it didn't, and the planet is tidally locked, then wouldn't we expect the atmosphere to have condensed to a solid on the planet's dark side?

    It's still a really exciting discovery in terms of mass and distance from star- we do seem to be closing in on a reasonably close Earth analogue.
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  6. #5  
    Moderator Moderator Dishmaster's Avatar
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    Quote Originally Posted by KALSTER
    The planet has three times Earth's mass and is only slightly more voluminous, so it will probably have quite a different atmosphere than Earth's, if I am not mistaken?
    The problem with the method of radial velocity is that it can only determine a mass minimum. The exact mass depends on the inclination of the orbit of that body.

    Yes I agree, it is an interesting result. But I totally disagree with the idea that science should compete with pop culture. Science is about the truth, the facts, not about entertainment or fashion - at least it shouldn't.
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  7. #6  
    Administrator KALSTER's Avatar
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    Quote Originally Posted by TheBiologista
    Quote Originally Posted by KALSTER
    Vogt even said that the chance is 100% that it has life. :?

    Still a great find though. The planet has three times Earth's mass and is only slightly more voluminous, so it will probably have quite a different atmosphere than Earth's, if I am not mistaken?
    Not sure they have a handle on the planet's radius do they? And unlikely they will unless they can directly image or observe a transit. Forgive me if I am well outside my understanding but the atmosphere will depend a lot on the radius, since the radius and the known mass will tell us the surface gravity, which currently we can't estimate. More gravity will tend to mean thicker atmosphere, all of which may well be irrelevant if that atmosphere did not have good heat distribution properties. If it didn't, and the planet is tidally locked, then wouldn't we expect the atmosphere to have condensed to a solid on the planet's dark side?

    It's still a really exciting discovery in terms of mass and distance from star- we do seem to be closing in on a reasonably close Earth analogue.
    I read the article from Yahoo where they do quote it as having three times Earth's mass and as being slightly bigger. The Nasa press release say it is three to four times as massive, but give no indication of volume.


    Edit: From the PAPER (Pdf):

    "However, if confirmed, the 37-day planet candidate offers a solid case for a potentially
    habitable planet in this very nearby system. The best Keplerian fit to the data indicates
    a 3.1M⊕ planet in a circular 36.6-day orbit of semi-major axis 0.146 AU. The dynamical
    stability investigations presented by Mayor09 also impose a lower bound on the orbital
    plane inclination, constraining the upper bound on the mass of GJ 581g to be no more
    than 1.6 times its minimum mass. We find a similar bound of about 1.4 assuming none
    of the orbital eccentricities exceed 0.2. So, the likely mass for this planet candidate is
    3.1 4.3M⊕. Using the results of Seager et al. (2007), the radius of GJ 581g is expected to
    be 1.3 1.5R⊕ if homogeneous and composed primarily of the perovskite phase of MgSiO3
    (Earth-like), or 1.7 2R⊕ if water-ice. All radii are predicted to be ~ 20% smaller if the
    planet is differentiated, so the planet is likely to have a radius below 1.5R⊕. The mass and
    radius estimates imply a surface gravity of ~ 1.1 1.7 g, very near that of the Earth."

    *The Lick-Carnegie Exoplanet Survey: A 3.1M Planet in the
    Habitable Zone of the Nearby M3V Star Gliese 581
    Steven S. Vogt1, R. Paul Butler2, E. J. Rivera1, N. Haghighipour3, Gregory W. Henry4,
    and Michael H. Williamson4



    Very interesting indeed!
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
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  8. #7  
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    They have even started speculating how life might look on the planet.

    http://io9.com/5653433/the-astrophys...n-second-earth
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  9. #8 Too bad.... 
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    Apparently, the argument of life or not, atmosphere or not, could have been resolved if only the planet transits the sun in line with us. Doing so would allow us to take a spectrograph of the planet's atmosphere and tell give us some potentially tantalizing details. Such as, whether or not oxygen is present. Which would implicate at least plant-ish life. Sigh. Good thing is, the search is only just beginning. Expect more of these types of discoveries in the near future!
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  10. #9  
    Forum Freshman AlphaParticle's Avatar
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    I'm no genius but aren't there just a few primary things needed for life on a planet such as, the correct temperature, a thick enough atmosphere, the correct elements on the planet, etc. but still, on the other hand, we know hardly anything about the universe so who knows, even if it's not exactly like earth, there may be a species adapted to it's environment.
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