Galaxy view up close

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JROYB

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Got into a heated debate about this last night............

Suppose you're aboard a spaceship with a large panoramic window, and close enough to a galaxy that it basically fills the window. Would the view be:

Just like the long exposure photos.......brightly and sharply detailed?

0r more or less like the gauzy view experienced through a telescope's eyepiece - albeit much larger and a bit brighter?

I'm in for the second option. While the galaxy is much closer, the human eye still has it's limitations.

Thoughts from the experts here?
 
O

origin

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JROYB":3apxbvz2 said:
Got into a heated debate about this last night............

Suppose you're aboard a spaceship with a large panoramic window, and close enough to a galaxy that it basically fills the window. Would the view be:

Just like the long exposure photos.......brightly and sharply detailed?

0r more or less like the gauzy view experienced through a telescope's eyepiece - albeit much larger and a bit brighter?

I'm in for the second option. While the galaxy is much closer, the human eye still has it's limitations.

Thoughts from the experts here?

Oh heck this is an easy one. On a clear night go outside and look up you are seeing a galaxy up close, it fills the entire sky. Every star that you are seeing is in this galaxy.
 
J

JROYB

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Now, why didn't I think of that? :lol:

I'll be sure to use this when my friends and I convene again.........
 
O

origin

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JROYB":37a42dhw said:
Now, why didn't I think of that? :lol:

I'll be sure to use this when my friends and I convene again.........

Good deal... Reminds me of (long ago) when I was arguing with this guy as what is the closest star to earth - he was saying Barnards star and I was saying alpha centuri. Of course some guy walks by as we are talking and say, "how about the sun"! Uh, oh yeah.... never mind.
 
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ramparts

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origin":2eoda47k said:
JROYB":2eoda47k said:
Got into a heated debate about this last night............

Suppose you're aboard a spaceship with a large panoramic window, and close enough to a galaxy that it basically fills the window. Would the view be:

Just like the long exposure photos.......brightly and sharply detailed?

0r more or less like the gauzy view experienced through a telescope's eyepiece - albeit much larger and a bit brighter?

I'm in for the second option. While the galaxy is much closer, the human eye still has it's limitations.

Thoughts from the experts here?

Oh heck this is an easy one. On a clear night go outside and look up you are seeing a galaxy up close, it fills the entire sky. Every star that you are seeing is in this galaxy.

Isn't this a different question, though? We have the galaxy surrounding us on all sides. The human eye can see no more than about 2/5 of the celestial sphere, so if this problem is assuming the galaxy to be wide enough that it just fills our field of vision, then there's a good amount of brightness put into a more compact space than in the simple example of our seeing stars in our galaxy (not to mention the galaxy's bulge will provide a bunch of brightness that we don't even see due to dust).

That said, you're probably right that the stars wouldn't look much different... I see no reason the galaxy would be hazy. Let's crunch some numbers, cuz it's fun. Take the Andromeda Galaxy (M31) as an example. The human eye can see about 120 degrees across, and M31 is about 20 kiloparsecs in diameter. Make a right triangle and you'll see that the distance to M31 then has to be 20/tan(60 deg) = 20/sqrt(3) kiloparsecs. Call that about 10 kiloparsecs since we're doing an order-of-magnitude calculation and 20 kiloparsecs is probably an overestimation of its visual width anyway. Now take its absolute magnitude (about -21) and plug into the distance modulus equation (m-M=5log(d)-5, with m and M the apparent and absolute magnitudes, respectively, and d the distance in parsecs) to find an apparent magnitude of a mere -6. This is way dimmer than I expected (assuming I calculated everything correctly, I'm a bit rusty with that distance modulus!). For comparison, check out: http://en.wikipedia.org/wiki/Apparent_magnitude but this is really only about 4 times brighter than Venus at its brightest (but of course, spread out over the whole sky). If you want to compare brightnesses using that table, then the ratio of an object's brightness to M31's brightness (in this problem) is given by 2.5^(m1-m2) where m1 is the object's magnitude and m2 is M31's of -6.
 
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origin

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There is actually a whole lot of factors you can take into account I suppose. If you are above the plane of the galaxy and have the center bulge be in your field of view that would be quite bright.

If you were looking at a galaxy that had considerable less dust than the milky way the side on view would be much brighter.

A irregular galaxy or a galaxy with an active core would be much brighter.

It seems that in many movies or video games the plain star background it just to boring so they always seem to put in fantastic looking nebula or galaxies but in reality these things are very faint only look really good if you take long exposure photos.
 
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SpaceTas

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You might want to chase up the thread "Seeing the Milky Way"

it is the surface brightness that matters for how "see-able" a galaxy is. This doesn't change with distance. So the galaxy looks the same surface brightness (glow) but larger when it is closer.

Andromeda example: at it's current distance of 178 kpc, it has an apparent size 3.166 x 1 deg. Reducing the distance to 43 kpc, so that the whole galaxy spans 90 deg means an increase in total brightness by a factor (778/43)**2 = 18x18 but the area has increases by 18x18 (18 is the ratio of tan(1/2angles) ie tan(45)/tan(3.166) or ratio of distances. So the surface brightness hasn't changed.


So the numbers show that going out to a dark sky site to see the Milky Way turns out to be a very good "simulation" of seeing a spiral galaxy close-up: which is what you're doing. Definitely recommended :cool:
 
O

Ortix

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Are we able to observe galaxies up close?

Let's say theoretically that I am a certain distance away from a galaxy such that it completely would fit in my field of sight from that certain distance. Much like being a certain distance from a house such that you are only able to see the house and nothing else around it (maybe some stuff to the sides if it's a tall house :p ). Would I be able to observe it from the window of let's say a super duper space ship like the woman did in the movie Contact?

Will they look the same as they do in the pictures?

I read somewhere that galaxies are far too faint for us to see with our naked eye and that telescopes take many hours (if not days) to capture the light of a galaxy on their CCD.
 
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ZenGalacticore

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Re: Are we able to observe galaxies up close?

One can see the Andromeda Galaxy--2.2 million light years away-- with the naked eye. As well, one can also see the Large Magellenic Cloud with the naked eye. (If you ever get a chance to visit the Southern Hemisphere.)

And if you were say, 100,000 or 200,000 light-years away from our Galaxy, you would have a splendid view of it. :)
 
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Saiph

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Well, the milky way would get brighter if you moved outside it, and above the plane. Mired in the disk as we are, a lot of light is blocked entirely by the dust lanes.

That said, while it would be impressive, and brighter, it would still be hazy except for some unusually dense star clusters.
 
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SpaceTas

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Sal
Saiph":1kq11u27 said:
Well, the milky way would get brighter if you moved outside it, and above the plane. Mired in the disk as we are, a lot of light is blocked entirely by the dust lanes.

That said, while it would be impressive, and brighter, it would still be hazy except for some unusually dense star clusters.

Yes the dust lanes block most of the bulge and the nucleus. But you can get a idea of how bright the bulge would look from the section we see in Sagittarius. It's a good glow, that can cast a very faint shadow. So I agree that the bulge would look brighter, and the nucleus would look a lot brighter (check the other thread; i did a rough calc.).

But if you go too far out of the plane you start seeing through the spiral arms (only 1,000 ly thick compared with thousands between spiral arms and dust lanes) ; reducing the surface brightness.

Also going out of the plane all the bright stars (eg like those in Orion through to Scorpio) will fade to insignificance if you move too far up. This was so for the proposed case in the other thread (above center about 60,000 ly; ie whole Milky Way spans about 90 deg edge to edge).

I think the best view would be just above the plane, so you can see the nucleus, the dome of the bulge, still get the over-laping of the star clouds of the spiral arms, and see thl brightest stars and local star cluster etc.

Maybe something like this but in shades of gray
kepler740-730.jpg
 
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