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Thread: Beginners Questions about Astronomy

  1. #1 Beginners Questions about Astronomy 
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    Hello,

    I have a few questions for astronomers.

    1) When you look up at the sky at night with the naked eye, are all those stars within the milkyway galaxy? Or can we see past our own galaxy and see stars from other galaxies mixed in with stars from the milky way?

    2) I heard the universe is 78 billion light years across. What is at the edge of the universe? And what happens if you go past it? I mean, i hear a lot of people say that there is no other side and the universe is all that is. Its not like the big bang happened in a vacuum, there is nothing then it expands. But lets say we did fly out to the edge and kept going, do you just bounce off the boundary? Or is it some freaky geometry that you would end up back where you started after a while?

    3) Is the sun going to burn out in 5 billion years?

    Cheers


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  3. #2 Re: Beginners Questions about Astronomy 
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    Quote Originally Posted by onemind
    1) When you look up at the sky at night with the naked eye, are all those stars within the milkyway galaxy? Or can we see past our own galaxy and see stars from other galaxies mixed in with stars from the milky way?
    All the STARS you see are, but you can if you use a telescope see galaxies. I believe the big dipper constellation is a cluster of them. Any stars and galaxies we see are not as we would see them as today, but however many light years away that many years ago. And seeing that the universe is not 78 billion years old, the fact that the universe is 78 billion light years across is only a theory.

    Quote Originally Posted by onemind
    2) I heard the universe is 78 billion light years across. What is at the edge of the universe? And what happens if you go past it? I mean, i hear a lot of people say that there is no other side and the universe is all that is. Its not like the big bang happened in a vacuum, there is nothing then it expands. But lets say we did fly out to the edge and kept going, do you just bounce off the boundary? Or is it some freaky geometry that you would end up back where you started after a while?
    Edge of the universe? I don't think there is one. There is supposedly a giant black hole at one end. There is no boundry (so the theory goes), the universe will continually expanding until all galaxies are so far apart that they die due to old age and half lifes occur and thus no universe. The anti of that theory is that the gravity of the universe will pull it all back together, which is called 'the big crunch'

    Maybe the freaky geometry would actually be cooler :wink:.

    Quote Originally Posted by onemind
    3) Is the sun going to burn out in 5 billion years?
    Yes if we don't interfere and if we are still around then we may have found a way to keep it burning for ever :-D.


    Quote Originally Posted by onemind
    Cheers
    Your welcome


    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  4. #3  
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    Thanks man

    Edge of the universe? I don't think there is one
    So what happens when you get to the edge if there is no edge?

    And good point about the universe not being 78 billion years, but it would only have to be 39 billion years old because it would be 39 in each direction from the singulaity. But if the universe is only around 14 billion years and it expanded at the speed of light it would be 28 billion light years across. Where did the extra 11 billion light years come from under that theory?
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  5. #4  
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    Quote Originally Posted by onemind
    Thanks man

    Edge of the universe? I don't think there is one
    So what happens when you get to the edge if there is no edge?

    And good point about the universe not being 78 billion years, but it would only have to be 39 billion years old because it would be 39 in each direction from the singulaity. But if the universe is only around 14 billion years and it expanded at the speed of light it would be 28 billion light years across. Where did the extra 11 billion light years come from under that theory?
    Because space expanded faster than the speed of light.

    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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    So what happens when you get to the edge if there is no edge?
    You can't get to the edge if there is no edge, can you? I mean for an edge to exist, there would have to be something on the other side of the edge. Space is bent so that You would eventually end up where you started. Remember that there is no such thing as the centre of the universe.
    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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  7. #6  
    The Doctor Quantime's Avatar
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    Quote Originally Posted by leohopkins
    Quote Originally Posted by onemind
    Thanks man

    Edge of the universe? I don't think there is one
    So what happens when you get to the edge if there is no edge?

    And good point about the universe not being 78 billion years, but it would only have to be 39 billion years old because it would be 39 in each direction from the singulaity. But if the universe is only around 14 billion years and it expanded at the speed of light it would be 28 billion light years across. Where did the extra 11 billion light years come from under that theory?
    Because space expanded faster than the speed of light.

    Do you know what this means? It means this damn--thing doesn't work at ALL!
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  8. #7  
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    Big Bang, suggest space expanded/expanding at near the speed of light and some say many times this speed. What we currently see (known universe) 14.2 billion light years away, is what was 14.2 billion years ago. Under the "near speed of light or C, the *current* location is at least 28BM in both directions or the 56BM across. Over C some say 156BM, for some reason. One alternative theory, although not generally accepted, the Steady State or *Always been there* Universe, makes or requires no determination of where the universe ends.

    Under BBT, and space is itself expanding, whats beyond is some form of nothingness. Under SSU space may be infinite (endless) and the universe, regardless of size, is in this space. BBT, you could not get to an edge, SSU, you would simply leave the universe where it ends.

    Its thought, the fuel in our Sun (Hydrogen), now about 50% exhausted, will be gone in 5 billion years or so. But the death of a star is more complicated. Long before the fuel is gone the Sun will expand, some think taking out life on Earth in a couple billion years or less.

    The Sun is 99.8% of the total mass in our Solar System. Jupiter makes up most of the rest and does have some hydrogen. But to keep the sun burning would mean adding Hydrogen. Think, if our species is going to survive, it would have to be in another Solar System...probably in far less than a billion year.
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    Re the stars you can see. If the conditions are correct and you have good vision, you can see the galaxy Adromeda. It will appear a faint, fuzzy patch. When you see that 'speck, you are looking at the combined light of 300,000,000,000 or so stars. Estimates vary but we can see a maximum of 15,000 stars in the Milky Way from both hemispheres of the Earth. The irony is that you see the combined light from 600,000 times as many stars outside of our galaxy than from our own....all those Adromeda galaxy stars, 300,000,000,000, are in that one faint fuzzy patch.
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  10. #9  
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    Thanks all

    Isn't life a trip :P

    Here is a cool vid made by ibm to show the size of the universe: http://www.atheistnation.net/video/?...zing-universe/

    stars. Estimates vary but we can see a maximum of 15,000 stars in the Milky Way from both hemispheres of the Earth.
    Is that all? I thought we could see millions. If its just an estimate why doesnt someone count them :P
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  11. #10  
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    That is really an amazing video, but I wish they would have given more definition to what you are actually seeing.
    The most important thing I have learned about the internet is that it needs lot more kindness and patience.
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  12. #11  
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    Here is the original without the techno music and commentary which explains what you are seeing: http://www.powersof10.com/index.php?...tch_powersof10

    YOu need to enter an email address to see it though. Just insert a faxe one, you dont need to activate or anything.

    Here is another good vid to put it all into perspective :P

    http://www.glumbert.com/media/monkeys
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  13. #12  
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    I never knew the human body was all made up of DNA, the dunce award goes to me.
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  14. #13  
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    wow google earth has really come on eh
    be nice im new
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  15. #14  
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    Like a monkey. I think humans have got to be the weirdest species on this planet, and who knows maybe the galaxy, or even the universe!
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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