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Thread: the shape of our galaxy

  1. #1
    Join Date
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    the shape of our galaxy

    watching an episode of QI I heard that we cannot know the shape of our own galaxy, ( how many arms to the spiral was how it was phrased), is that true?

  2. #2
    Join Date
    Dec 2004
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    12,534
    It is slightly easier to map out the arms of the Milky Way
    than to map the arms of some other spiral galaxy which
    happens to be edge-on to our view. But not much easier.
    Try to determine how far away a cloud of gas and dust is
    that you can't see because it is hidden behind another
    cloud of gas and dust...

    Just look at any image of the whole sky to see the problem.

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  3. #3
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    I balk at the word "cannot". How old was the episode? Who said it?
    We have a lot of ways of determining the geometry of our galaxy, whether you are looking at star locations, bright star locations, gas and dust locations. All of these have some difficulty and a little (usually resolvable) ambiguity, because we are looking through all the material. But with IR and radio observations that penetrate everything, we can overcome that difficulty. I think that today we have a pretty good picture of the shape of the galaxy... though there is room for that to improve.
    Forming opinions as we speak

  4. #4
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    Thanks I viewed it last night but it was a few years old, I do not know how old. Stephen Fry was in the chair as usual.

  5. #5
    Join Date
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    I'm impressed that they have determined that we are a barred spiral galaxy. It is awe-inspiring to think how much we know and even more about how much we don't know I love science...now if I could just find a single woman that is the same that thinks I'm attractive

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