Could we see galaxies while in a spaceship?

Discussion in 'Science and Technology' started by FPAlpha, Sep 19, 2010.

  1. FPAlpha

    FPAlpha Vice Admiral Admiral

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    So i was surfing around doing some link hopping and ended up on a Wiki article about galaxies.

    I've always wondered that if someone would be on a spaceship moving through deep space would it be possible to see galaxy disks with your own eyes?

    Imagine the final shot of Empire strikes back when Luke and Leia look out of the window and see this huge galaxy disk in front of them.

    Is that physically realistic or possible? (as realistic as possible given that there are spaceships that are so far out)
     
  2. Deckerd

    Deckerd Fleet Arse Premium Member

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    I think the distances involved would still be a problem for human eyes. If you were far enough away to see the whole thing, you would probably not see very much.
     
  3. Asbo Zaprudder

    Asbo Zaprudder Rear Admiral Rear Admiral

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    They're pretty faint unless you're just about inside one -- for example, think how the Milky Way gets washed out of the night sky by lights in towns and cities. M31, the Andromeda Galaxy is 2.5 million light years away and 3 degrees across as seen from Earth (6 time the apparent diameter of the Moon) yet it only looks like a faint smudge to the eye.
     
  4. JustAFriend

    JustAFriend Commodore Commodore

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    If you were thousands of light-years outside the Milky Way in one of the globular clusters that orbit it you'd see that.

    Of course you can see a galaxy disk NOW, just go out to a really really dark area and if you have reasonable vision and know where to look you can see Andromeda yourself (helps to look to the side of it and use your peripheral vision which is more sensitive than looking directly at something...)
     
  5. Owain Taggart

    Owain Taggart Rear Admiral Rear Admiral

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    You could probably see the Milky Way from a different angle than you do from Earth.
     
  6. Silvercrest

    Silvercrest Rear Admiral Rear Admiral

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    The Empire thing is not a very good example-- it's visibly rotating. Something the size of a galactic disk, at the apparent distance where Luke and Leia were viewing it, would have to be spinning faster than the speed of light to have visible rotation. So whatever they saw was not a galaxy.

    I know this doesn't help answer the question. The real answer is, sure, you could see galaxies. But they wouldn't look like that. :p
     
  7. Christopher

    Christopher Writer Admiral

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    Not really. To the naked eye, it would look very faint from that distance. I mean, we're in the galaxy, but our side-on view of its disk is only as a very faint strip of light across the night sky, one that you can only see if your eyes are sufficiently dark-adapted. If it's so dim from a position directly inside it, it's not going to be brighter from thousands of parsecs away.

    All those TV and movie space shots where we see starships against backdrops of brilliant, colorful nebulae and galaxies and whatnot are all bogus, because the brilliant, colorful astronomical photos they're based on are the result of very long exposure times and image enhancement to make them look prettier.

    Of course, as you say, some galaxies are faintly visible to the naked eye from Earth, and they would be more clearly visible from space, without the Earth's atmosphere to absorb and scatter the light. They'd still be faint, though.



    Only if you travelled thousands of light-years away from Earth. Although your best bet would be to travel perpendicular to the plane of the disk. From most anywhere within the disk, the edge-on view that the ancients named the "Milky Way" (which in Latin is Via Galactica, the origin of the word "galaxy") is going to look generally similar. But the disk is fairly flat, only around a thousand light-years thick, so you wouldn't have to travel as far in a perpendicular direction to get "above" or "below" it and see a perspective shift.
     
  8. Udat

    Udat Rear Admiral Rear Admiral

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    Never seen it! But I will look next time I have a chance when I`m out of town
     
  9. Asbo Zaprudder

    Asbo Zaprudder Rear Admiral Rear Admiral

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    Never seen the Milky Way (and many city-bound folks haven't) or never seen M31?
     
  10. BolianAuthor

    BolianAuthor Writer, Battlestar Urantia Rear Admiral

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    I WANT to see Andromeda with my naked eyes so badly... I have seen the extremely faint version from my folk's home in Torrance, Cali, but I want to see it from way out in the country, where there is less light pollution.

    If you were far/close enough away from the galaxy, you WOULD be able to see the whole disk, just on the basis that it's massive concentration of stars bunched together... YES, they are millions and billions of miles apart, but if you look at the night sky in a clear sky, you can see millions of stars that you don't normally see in the city. The sky looks quite full then.

    So if you are far enough away, you will be able to see the disk... but yeah, you won't see it spinning.
     
  11. Asbo Zaprudder

    Asbo Zaprudder Rear Admiral Rear Admiral

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    Even through telescopes, M31 looks like a blur to the eye and you mostly see the galactic core regions. In 1887, powerful telescopes and long photographic exposure times were first used to resolve the spiral structure in detail.

    From several tens of thousands of light years above the plane of our galaxy, the arms would be relatively faint and the view would be dominated by the bright core region.

    You would be able to tell the galaxy was spinning if you measured the red and blue shifts, or if your lifetime were measured in many millions of years.
     
  12. Somerled

    Somerled Ensign Newbie

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    Provided you in the shade of the spaceship, then the galaxies will be easier to see because -
    1) no atmosphere to absorb / scatter the light from them
    2) no light pollution to overwhelm the light from them
    3) higher contrast (they will stand out more against the blackness of space).
    But you are still limited by the size of the lenses in your eyes (this wont change).

    Close galaxies like the Andromeda Galaxy, the Large and Small Magellianic Clouds would be very much more spectacular in space than on the ground.
     
  13. Mr_Homn

    Mr_Homn Fleet Captain Fleet Captain

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    the thing at the end of empire strikes back was not a galaxy
     
  14. Ronald Held

    Ronald Held Rear Admiral Rear Admiral

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    "see" means in the human visual spectrum?
     
  15. KJbushway

    KJbushway Commodore

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    Yeah i agree with what she said, it might just be to much for us even at a distance.
     
  16. EmperorTiberius

    EmperorTiberius Captain Captain

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    I don't understand why not if you were right outside of it. You'd see the nearby stars while the far areas would appear white, right??
     
  17. Christopher

    Christopher Writer Admiral

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    Even if you were in Earth orbit with no atmosphere or city lights in the way, your naked eye could only discern stars within a few dozen parsecs, maybe a few hundred for the brighter ones. Our galaxy is a hundred thousand light-years across. Even if you were "right outside of it," most of it would just be too dim for your naked eyes to see. If you think about it, that's just common sense. If you could see the galaxy clearly from outside it, then from our position inside it, the night sky would be perpetually white, not black. The reason the night sky is dark is because most of the galaxy's stars are too far away to see with the naked eye. And if you move outside the galaxy, they get even farther away. At best, from a position not far outside the galaxy, you could make it out as a faint gray blur.
     
  18. tauntme

    tauntme Lieutenant Commander Red Shirt

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    Dude, this just blew my mind.

    So if we were to be perpendicular to the Milky Way, we wouldn't see the Milky Way like we see it in the artist renderings and illustrations?

    So we wouldn't see something like this?
    [​IMG]
     
  19. Silvercrest

    Silvercrest Rear Admiral Rear Admiral

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    You're inside it now. If the artists' renditions were realistic, you should be able to see some form of that picture already, except at close range. Granted, the arms and whirly-things wouldn't take the same shape, but you'd certainly be able to see the big glowing galactic core.

    Odds are that if you look at the night sky, you can't see a huge glowing object other than the Moon. But if you do see one, PM me.
     
  20. Christopher

    Christopher Writer Admiral

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    Not with the naked eye, no. As I said above, astronomical pictures like that are created by taking long exposures with sensitive telescopes, and generally by artificially enhancing the images with false or exaggerated colors. Open that image in an editing program, dial down the brightness, contrast, and color saturation considerably, and then you'll approach what the unassisted human eye could probably make out.

    Like I said, it's just common sense. If the galaxy could look that bright from hundreds of thousands of light-years away (the distance you'd need to see its full disk), then from our perspective within the galaxy, the Milky Way would be blinding. But it isn't. It's quite faint to the naked eye. True, that's partly because most of it is hidden behind dust clouds, but even the parts that aren't hidden look fairly dim compared to the few thousand bright nearby stars we can make out. And that's because they're far away. From a position where you could see the whole galaxy, they'd be much, much farther away, and thus much, much dimmer.