Seeing the Milky Way

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Kmand

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If there was person on the surface of a planet that was orbiting a star a few (tens of) thousands of light years above the galactic plane, perhaps in one of the dwarf galaxies orbiting the Milky Way, would he be able to see (with only the naked eye) a giant Milky Way in the night sky above him? Would that view be absolutely breathtaking or would it be just some fuzzy barely visible outline or somesuch?
 
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Saiph

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Depends on how far away he is. I find the view we have here breathtaking. But it is diffuse, as we're basically inside it and there are dust clouds.

I'd imagine that if you get above the plane, and far enough out that it starts looking like a galaxy you'd get some spectacular naked eye views that cover huge stretches of the sky.
 
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MeteorWayne

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As an interesting comparison, consider the Large and Small Magellanic Clouds at ~ 160,000 and 200,000 ly away, visible from the tropics and the southern hemisphere. A face on view of the Milky Way at that distance would probably be QUITE spectacular.
 
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AnalynSarte

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yah, it depends on the position of the person.

"The Milky Way is a hazy band of light that can be seen encircling the night sky.
All of the stars in the night sky are residents of a galaxy - the Milky Way. We are also residents of this galaxy. The Earth orbits the Sun, and the Sun orbits the center of our galaxy. Because of our position, we can see some of the galaxy as a band stretching across the sky."

Science News and Reasearch
 
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crazyeddie

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Kmand":34s9strz said:
If there was person on the surface of a planet that was orbiting a star a few (tens of) thousands of light years above the galactic plane, perhaps in one of the dwarf galaxies orbiting the Milky Way, would he be able to see (with only the naked eye) a giant Milky Way in the night sky above him? Would that view be absolutely breathtaking or would it be just some fuzzy barely visible outline or somesuch?
The view would be pretty similar to what you can see now in a dark-sky location, except that instead of a band of diffuse light, the Milky Way would appear as a huge, rather dim, oval-shaped disk. The center of the galaxy, which is invisible to us due to intervening dust clouds, might appear relatively bright in comparison. But unfortunately, it would look nothing like the spectacular photographs of the galaxies you see from space and ground-based telescopes.
 
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dragon04

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I would think that if one lived on a world 50 or 60,000 LY distant from and significantly "above" or "below" the Ecliptic, they'd have quite the spectacular view. Especially with a very dark night sky.

Let's say that relative to the galactic core, you're at the Zenith. Straight up from it and perpendicular to the plane of the galaxy. What I don't know is how much of the MW you could see from one end to the other. The galaxy is about 100K LY across and at 60K LY away, I don't know if the whole galaxy would "fit" in any observer's night sky.
 
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halcyondays

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Surprised none of you have yet mentioned that Carl Sagan had this idea more than 20 years ago in one of his Cosmos episodes. He envisaged a "galaxy rise" from a planet round a star in a globular cluster above the plane of a spiral galaxy, and showed it rising from the horizon covering half the sky.

Check out this clip starting from 4:50... "Not a sunrise, but a galaxy rise..."

http://www.youtube.com/watch?v=qEXGyyoh_og
 
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crazyeddie

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halcyondays":3v4jo271 said:
Surprised none of you have yet mentioned that Carl Sagan had this idea more than 20 years ago in one of his Cosmos episodes. He envisaged a "galaxy rise" from a planet round a star in a globular cluster above the plane of a spiral galaxy, and showed it rising from the horizon covering half the sky.

Check out this clip starting from 4:50... "Not a sunrise, but a galaxy rise..."

http://www.youtube.com/watch?v=qEXGyyoh_og
I think Carl was engaging in a little artistic license in that clip. Galaxies just aren't that bright, visually.....even nearby ones. I mean, we're completely surrounded by our own galaxy, which is a close as you can get, and yet we can only see it under the darkest of skies.
 
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Saiph

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I think we could get a lot brighter than we see here. Here we've got tons of dust clouds obscuring our view, and we've got the entire brightness spread out over a giant ring around our sky. Receed a bit and I actually think the surface brightness will increase as you cram the entire galaxy into a smaller area, and rise above the plane of the dust clouds, allowing you to see more stars.
 
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SpaceTas

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Being a southern hemisphere person my first reaction was a comparison with the Large Magellanic Cloud.
It is quite distinct and looks like a piece of detached milky way. Under dark sky conditions you can just see the Tarantula nebula .... which means it is intrinsically vastly brighter than Orion. They go very high in the sky from Tasmania.

Also from the southern hemisphere the galactic center and bulge goes overhead. In very dark sites you can see faint shadows.

A better comparison in the Andromeda galaxy. The Milky Way is a bit dimmer. So as a first estimate the Milky Way would look like Andromeda from a distance of 2 million light years ie on a dark night a easily noticeable fuzz brighter in the middle about 1 deg across.

Estimating what the Milky Way would look like from say the LMC or closer 50,000 (dragon04) light years is trickier.

The key is the surface brightness. Take Andromeda, if you half the distance the total brightness will go up by a factor of 4 (inverse square law) but the area will also go up by a factor of 4 (each side of square will appear twice as long) so the overall surface brightness stays constant. Cavet: this is based on small angle approximation and could break down, but will hold for each part of the galaxy we look at. So I will continue along these lines.

So the surface brightness stays the same. So the contrast between the Milky Way and the sky of our hypothetical planet will be about the same as for here on Earth. The Milky Way will look about as bright but bigger, and point like objects clusters, nebulae, stars will look brighter on the background.

Now most of the Milky way we see in the sky is disk, the brightest surface brightness (most stars in an area) is toward the bulge. Away from the dust lane there is about 1 to 2 magnitudes of extinction (absorption) caused by dust. So the outer bulge would look 2-4 times brighter. The center of the bulge is blocked from view, but taking the bulges as a giant globular cluster the central region would be another 2 magnitudes brighter (roughly from how I remember globular clusters: a lower limit estimate can be made by considering slices through a uniform ball of stars about 2 times brighter (1 magnitude), but stars are much more packed at the center in globulars, and the bulge). So we have 4 magnitudes, lets be generous and give it 5 (= nice 100 x factor) magnitudes brighter when view unobscured.

So from the LMC you would have a tilted disk about 35 deg across (trig here: half size galaxy 50,000 ly, distance 160,000 ly , half angle=ArcTan (50/160) =17 deg) with a bulge about 3-4 deg across starting twice as bright as the Milky Way (as seen from Earth) and getting brighter in the middle. (Bulge about 10,000 ly across). The bulge would look like the head of a large bright-ish comet, Hyakutake maybe). Depending on tilt the disk surface brightness would be comparable to what the Milky way looks like or the LMC. You would be just able to spot the few very brightest stars and nebulae.

Now from only 50,000 light years the disk of the galaxy would look be about 90 deg from edge to edge (easy triangle 50,000 ly distance, half size 50,000 so 45 deg triangle). Unfortunately from above the surface brightness of this disk would be much lower than how we see the Milky Way because you would be looking through the thin disk rather than along the disk. It would be like looking away from the Milky Way in our skies without the stars. Everything except the bulge would be further away than 50,000 ly. Only a few super massive, super bight stars would be visible, with a few extreme nebulae and clusters. Recall M13 globular is only 25,000 ly and is just visible. Now the bulge could look much more interesting. It would be 11-12 deg across and look maybe 40 -- 100 times brighter than any patch in the Milky Way: like a big bright comet head (say a large version of Hale-Bopp).

Maybe the best view is just above the plane near the edge of the galaxy.

After doing this thought experiment I am a bit disappointed.
Nothing like the Cosmos galaxy rise.

Now for s spectacular sky, live in/near the bulge or in a globular cluster. A sky covered with hundreds of stars the brightness of Venus on a nearly uniform glow of stars.
 
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kg

Guest
The Andromida galaxy is a naked eye object. To my eye it looks like a fuzy point of light. I'm assuming that I am seeing the bright cerntral bulge. When I look at it through my 8" Celestron at low magnification Andromida fills the whole field of view much the same way the full moon would. Would Andromida appear in the sky to be the same size as the full moon if your eyes could gather enough light to see it? Would an observer outside the milky way have a similar problem seeing the milky way?
 
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MeteorWayne

Guest
The Andromeda galaxy is many times larger than the full moon, if we could gather the light. It would be about twice as high, and six times as wide as the full moon.
 
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MeteorWayne

Guest
A related comment in an SDC article today about a new group of stars found in the Milky way.

"Some of these stars follow eccentric comet-like tracks that take them deep into the center of the Milky Way. Others swoop far beyond the sun's own orbit. In fact, most spend most of their time thousands of light-years above or below the disk of the Milky Way.

"Someone living on a planet around one of these subdwarfs would have an incredible nighttime view of a beautiful spiral galaxy — our Milky Way — spread across the sky," Burgasser said.

:)

Full article:

http://www.space.com/scienceastronomy/0 ... warfs.html
 
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SpaceTas

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Meteor Wayne. Yes I just spotted the article as well. Nice co-incidence.

As I said in previous post the view of our Milky Way from high above the galactic plane won't look spectacular, because you are a long way from the stars and nebulae, and you are looking through the galaxy. The plane of the galaxy is something like 10,000 ly thick while when we look toward Sagitarius (toward galactic bulge) we are seeing along a line of sight of 30,000+ ly to the bulge. This will be at least a factor 3 worse (1 magnitude) than what we see from here.

I think this idea of a spectacular view may be an ingrained myth. Maybe its worth doing a proper simulation but when will I have time .... Maybe some-one can push their planetarium software (send it 30,000 toward a galactic pole, with all stars loaded). I never needed the software so never bought any.

The descriptions of Andromeda are from what I recall, seeing it from dark sites in Turkey, and on top of La Palma, The Magellanic clouds descriptions come from many nights viewing in Australia, New Zealand and Chile. :)
 
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what4

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Thank goodness 4 people like Carl Sagan. He was 1 of the great inspiring intellects, of the last generation. He defied religious dogma BS that has & still dominates human-kind, with elegance. Fortunately there's still some, who do not believe thy know everything & also know what to believe. If you get my drift?
 
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