decent distance in light years

Discussion in 'Astronomy, Exobiology, & Cosmology' started by oiram, Dec 14, 2008.

  1. oiram Registered Senior Member

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    Most scientists theorize the high probability of life on other planets and I read that 30 million light years away, is still considered relatively close to planet earth to have life. The possibility of life to exist within this distance of 30 million light years is likely but the farther from the planet earth the higher the probabilities exist. The only requirement is a planet with water which scientists have confirmed several planets in the Milky Way show evidence of water including one of Saturn’s moons. My question is how far would be considered a decent distance to be out of the Milky Way and deep into space? 300 Million Light years?

    (After all if space is infinite then what even try to measure it?)
     
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  3. mathman Valued Senior Member

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    The diameter of our galaxy is around 100,000 light years. Also it has around 100 to 200 billion stars. I suspect that there is a fairly high probability that life exists somewhere among all these stars, as well as here.

    The Andomeda galaxy (our nearest neighbor) is around 2.5 million light years away.
     
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  5. oiram Registered Senior Member

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    I wish I knew as much about space as many f the people here on SF. I loved the move “K-Pax” and the thought of how real it was, as well as “Contact” starring Jodie Foster
     
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  7. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Ever see the series Cosmos? Here is a free download of it that I'm sure you will enjoy if you haven't seen it yet. It shows you many interesting things about the universe as you will see.



    http://www.google.com/url?sa=U&star...3IyBCg&usg=AFQjCNHv1vRZzYZuWLZQ4aEyY7EcLR21fQ
     
  8. D H Some other guy Valued Senior Member

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    Some (not most) scientists conjecture (not theorize) the high probability of life on other planets. The lay press is more wont to talk to the more outspoken subset of scientists who believe in these conjectures.


    First off, do you have a link?

    The important question: What kind of life? Primitive life? Multicellular life? Animal life? Intelligent life? Communicative life? Primitive life plausibly started within a billion years after the formation of the Earth, and very soon after the Earth had cooled to the point where it could sustain life. Multicellular life took another couple of billion years to appear and animal life, another billion plus years. Intelligent life, depending on how you define it, has been around for a few tens of thousands to a few tens of millions of years. Earth has had a communicative life form (life capable of communicating with species on other stars), for about one hundred years.

    Extrapolating from a sample of one is always a dangerous thing to do. However, we only have a sample of one available. Based on this sample, I would conjecture that if a planet forms that can sustain life it probably will have life, and that life will probably be in the form of primitive, single-celled organisms or relatively simple plant life.

    So, what are the odds of a planet forming that has even a ghost of a chance of sustaining life? Recent discoveries in astronomy suggest the odds are pretty slim. While there are an estimated 100 to 200 billion stars in our galaxy, most come in the form of multiple star systems. A stable planet orbit exists in such systems only if the planet distance between the planet and closest star is much, much less or much, much more than the distance between the stars in a multi-star system. Either way, we can rule out most multi-star systems. Most of the remaining stars are too close to the galactic center (too much radiation and too many nearby stars to make planetary orbits unstable) or too far from the galactic center (not enough iron or other metals).

    Of those that remain, it appears that most star systems form hot jupiters. These hot jupiters clear the intervening space of planets between where they form (10-20 AU) to where they finally end up (a fraction of an AU). Of those very few that do form an orderly star system like ours, how many have a planet that formed in the terrestrial zone and were walloped with a slightly smaller object that stripped off the primitive atmosphere (e.g., the Moon)?

    That, too is conjecture.
     
  9. OilIsMastery Banned Banned

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    The speed of light is not a constant c and red shift does not indicate what scientists think it does so the diameter of the galaxy is unknown and no one has counted the number of stars except God.

    "He telleth the number of the stars; he calleth them all by their names." (Psalm 147:4)
     
  10. D H Some other guy Valued Senior Member

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    You are trolling, OIM.
     
  11. OilIsMastery Banned Banned

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    You think anyone who has true opinions is trolling.
     
  12. Janus58 Valued Senior Member

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    Since Doppler shift is not used to determine the diameter of the Galaxy, this is a non-sequitur.
     
  13. OilIsMastery Banned Banned

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    How do you determine the diameter of the galaxy?
     
  14. James R Just this guy, you know? Staff Member

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    This is a lie. The speed of light in vacuum is constant.

    This is a lie.

    This is a lie.

    If you don't know, don't make false pronouncements as if they were facts.
     
  15. OilIsMastery Banned Banned

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    No such thing as a vacuum therefore no constant.

    So what's the answer?
     
  16. Trippy ALEA IACTA EST Staff Member

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    One method used is basic Trignometry - you know, the stuff they covered in Highschool.
     
  17. OilIsMastery Banned Banned

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    OK so what is the diameter of the galaxy and how did you measure it? Using what unit of length?
     
  18. James R Just this guy, you know? Staff Member

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    This has been explained to you in the past. Did you forget?

    Read the following article on the Cosmic distance scale. You may ask me if you have any further questions.

    I would also appreciate a "thankyou" for providing this link for you.

    http://en.wikipedia.org/wiki/Cosmic_distance_ladder
     
  19. OilIsMastery Banned Banned

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    If I recall there was unanimous consent in that thread that you are wrong and there is no such thing as a perfect vacuum.

     
  20. James R Just this guy, you know? Staff Member

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    OIM:

    You are being disingenuous, as usual.
     
  21. OilIsMastery Banned Banned

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    How so?
     
  22. oiram Registered Senior Member

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    Wow I asked a simple question and hadn’t expected such a debate amongst the experts. I am feeling lost, so hey guys try to bring down to a level for me because I am slower than a turtle. This is where I originally saw what caused me to ask the question. I am fascinated by space and the possibilities as portrayed in the movies, especially the movie K-Pax.

    The thought of the main character Proat in the science center planetarium showing the scientists information that came to him so naturally but that caused the scientist to struggle and be amazed was funny, although I am not sure how true to planets are Kevin Spaceys character was naming or describing.
    At any rate here is the link

    http://www.msnbc.msn.com/id/28148553/
     
  23. D H Some other guy Valued Senior Member

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    Whether a perfect vacuum can exist has nothing to do with the validity of the definition of c as the speed of light in vacuo. In claiming that a perfect vacuum cannot exist you are creating a straw man.
     

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