Galactic Habitable Zone

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Datura, Feb 3, 2005.

  1. Datura surrender to nothing Registered Senior Member

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    closest planet to the solar system

    I need to know how many light years away from Earth this is. The only thing I can find online is, "The sun is 29,000 l.y. away from the galactic center."


    *edit*

    Ok, Now I just want to know what the closest planet is that is not in our solar system.
     
    Last edited: Feb 4, 2005
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  3. Lucas Registered Senior Member

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    I don't think that there's a portion of the galaxy that can be called "galaxy habitable zone". Habitable in the standards that we are used means that the place must have a minimum of heat, so any planet around a star is potentially a place for the flourishment of life, and stars are distributed throughout the disk, and there are also stars in the halo. Is possible that exist also "rogue planets", a kind of planets wandering through the ISM without any star that can warm them, life in those planets is very unlikely to exist
     
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  5. blobrana Registered Senior Member

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    Hum,
    i haven’t checked, but the word on the street, is that the <a href="http://www.obspm.fr/encycl/GJ436.html">Planetary system GJ 436</a> in the constellation Leo is currently the closest.
    But they discovery them all the time...

    <a href="http://www.obspm.fr/encycl/cat1.html">See!</a>

    As for the "galaxy habitable zone" i imagine that it’s best for life to avoid the inner 10,000 ly portion of the galaxy as it’s pretty crowded (<i>with its associated supernova explosions and close encounters that disrupt Oort clods etc</i>), also there is always the danger that the resident black hole may spew out a jets of high-energy x-rays/particles...
    The safest bit would be in the relative calm of the outer fringes (of course avoiding the spiral arms)...
     
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  7. mathman Valued Senior Member

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    I believe our solar system is in one of the spiral arms.
     
  8. confusedSQL Registered Member

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    Indeed it is.

    Please Register or Log in to view the hidden image!

     
  9. Sagebrush Registered Member

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  10. Ophiolite Valued Senior Member

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    9,232
    Here is a quote from http://www.spacetoday.net/Summary/2105. This also has several related links:
    “Astronomers have determined that up to one-tenth of the stars in the Milky Way galaxy lie in a habitable zone that would permit that to have planets that could harbour life. The research, by Australian astronomers and published in Friday's issue of the journal Science, determined that a ring-shaped habitable zone opened in the galaxy 25,000 light-years from its core eight billion years ago. The ring has since expanded and now includes stars as young as four billion years old. The zone's size and location is based on a number of factors, including the presence of heavy elements needed to form planets and stars located a safe distance from supernovae.”

    There is a good summary here http://www.american-buddha.com/habit.zones.astron.htm. The importance of high metallicity (elements heavier than hydrogen and helium); low galactic orbital eccentricity (so avoiding frequent crossing of spiral arms; and distance from the galactic centre, are all emphasised.
     

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