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Old 10-30-2011, 10:50 PM
 
Location: Sarasota, Florida
15,395 posts, read 22,481,557 times
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Quote:
Originally Posted by NightBazaar View Post
That's right. You'd have to be a long way above or below the galactic plane to see the arms. From our position in the galaxy, we can't directly see them because of all the gas and dust. Our solar system is thought to be located in a spur called the Orion Spur, between a couple of major arms. As far as I can tell, the Milky Way is either a spiral galaxy or a barred spiral galaxy. Based on evidence collected by the Spitzer Space Telescope, it's probably a barred spiral galaxy.
A Map of the Milky Way

The Milky Way Has Only Two Spiral Arms

A Roadmap to the Milky Way - NASA Spitzer Space Telescope
Currently I agree......our home is now thought to be a Barred-Spiral Galaxy.

Barred spiral galaxy - Wikipedia, the free encyclopedia

Milky Way

Bars in Spiral Galaxies May Disappear and Reform in Ongoing Cycle - Technology Review

Bars kill spiral galaxies - Astronomy Magazine

BARS Project Web Page
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Old 10-31-2011, 07:00 AM
 
13,134 posts, read 40,564,287 times
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Quote:
Originally Posted by NightBazaar View Post
I think I see what you're talking about regarding what appears to be a spiraled look. The brightest hazy band in the photo is the direction of the galactic center. Just to the right of it is a light band, which looks like part of a curving arm or spur that's partially obscured by the trees, but we're looking at dust and we're only seeing portion of whole thing. The reason it looks like it does is because the camera used doesn't have the magnification to bring out more detail. Below is an image from a different angle which shows much greater detail. I can see the same streaky patches of dust. I think if you rotated the picture in your link, you might see the same features. Part of the problem is that the photo in the link you posted, although it's very cool, shows less of it than in the image below.
http://upload.wikimedia.org/wikipedi...33a-07_rsz.jpg
I knew that you'd have an answer NB and looking at your posted photo shows what appears to be the same similar pattern of a ''spiraled arm'' and so i was pondering about when i used to camp out in one of the state parks in new mexico out in the middle of the desert as you can see thousands upon thousands of stars (no light polution) in the night sky and yet i never recalled seeing what looked like a spiral arm pattern
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Old 10-31-2011, 07:04 AM
 
13,134 posts, read 40,564,287 times
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Quote:
Originally Posted by PITTSTON2SARASOTA View Post
Hey 6 Foot......

As far as I know you cannot see the spiral arms of our galaxy because we are imbedded in one of the spiral arms, within the galactic plane(disc); 26,000 light years from the galactic center......and much of the galaxy is obscured by dust....

In other words...... we have no direct way to see the arms because we cannot get images from above/below the galactic plane.

Here are some interesting links verifying my post and containing some interesting facts about our "home".

Nature of the Universe (http://www.physics.hku.hk/~nature/CD/regular_e/lectures/chap18.html - broken link)

Ten things you don’t know about the Milky Way Galaxy | Bad Astronomy | Discover Magazine

The Shape of the Milky Way

The Milky Way from Earth

ChView - THE STARS OF THE MILKY WAY

NASA - Milky Way Galaxy

Milky Way - Wikipedia, the free encyclopedia



Image courtesy of N.A.S.A.
Thanks for the info about the Galactic Plane PITTS and i'll check out your posted links when i've had some more coffee later this morning .
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Old 10-31-2011, 07:24 AM
 
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Here is a free planetarium program that will help you learn the starry night:

Stellarium
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Old 10-31-2011, 08:58 AM
 
5,463 posts, read 9,614,821 times
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Quote:
Originally Posted by 6 Foot 3 View Post
I knew that you'd have an answer NB and looking at your posted photo shows what appears to be the same similar pattern of a ''spiraled arm'' and so i was pondering about when i used to camp out in one of the state parks in new mexico out in the middle of the desert as you can see thousands upon thousands of stars (no light polution) in the night sky and yet i never recalled seeing what looked like a spiral arm pattern
Pareidolia? If you look at various shapes long enough, you can start to make out all kinds of patterns and shapes that can remind us of other things we're familiar with. Recently I saw a photo what what's being called the Pacman Nebula for its overall shape. It doesn't exactly remind me of Pacman, but apparently someone thought it did. Then there's the Horsehead nebula, which does look sort of like a horse's head. Of course, there's the Happy Face crater (Galle Crater) on Mars, as wel as various constellations. It could be someone saw what they thought looked like a spiral arm of the galaxy, but it's just the particular configuration of massive amounts of gas and dust backlit by light from the center region. As mentioned, we can't directly see the arms of the galaxy because of our position and point of view in it. We're just specks in a really BIG galaxy, kind of like fleas trying to look at the curvature of the entire Earth. LOL! Regardless, looking at the Milky Way with the naked eye at night, as you mentioned, is an impressive sight.

APOD: 2005 August 23 - NGC 281: The Pacman Nebula

http://photoblog.msnbc.msn.com/_news...ares-its-teeth

"Happy Face" Crater on Mars

Last edited by NightBazaar; 10-31-2011 at 09:44 AM..
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Old 10-31-2011, 03:59 PM
 
3,423 posts, read 3,207,047 times
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Quote:
Originally Posted by NightBazaar View Post
Pareidolia? If you look at various shapes long enough, you can start to make out all kinds of patterns and shapes that can remind us of other things we're familiar with. Recently I saw a photo what what's being called the Pacman Nebula for its overall shape. It doesn't exactly remind me of Pacman, but apparently someone thought it did. Then there's the Horsehead nebula, which does look sort of like a horse's head. Of course, there's the Happy Face crater (Galle Crater) on Mars, as wel as various constellations. It could be someone saw what they thought looked like a spiral arm of the galaxy, but it's just the particular configuration of massive amounts of gas and dust backlit by light from the center region. As mentioned, we can't directly see the arms of the galaxy because of our position and point of view in it. We're just specks in a really BIG galaxy, kind of like fleas trying to look at the curvature of the entire Earth. LOL! Regardless, looking at the Milky Way with the naked eye at night, as you mentioned, is an impressive sight.

APOD: 2005 August 23 - NGC 281: The Pacman Nebula

PhotoBlog - Pacman Nebula bares its teeth

"Happy Face" Crater on Mars

When you look at the mighttime sky (it is best to do this in the summer when the milky way is most visible all night long), and see the Milky way, you are seeing it edge-on. As such, you are seeing the dust lanes overlap one another. What's worse, we cannot see the opposite side of the galaxy at all, since it is oscured by what we can see. As such, you cannot truly discern the spiral nature of the galaxy by simply viewing it in the sky. It wasn't until astronomers mapped out the structure (by 3-d map placement of objects located within it) that it was recognized to have a spiral struture.
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Old 10-31-2011, 06:44 PM
 
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Quote:
Originally Posted by orogenicman View Post
When you look at the mighttime sky (it is best to do this in the summer when the milky way is most visible all night long), and see the Milky way, you are seeing it edge-on. As such, you are seeing the dust lanes overlap one another. What's worse, we cannot see the opposite side of the galaxy at all, since it is oscured by what we can see. As such, you cannot truly discern the spiral nature of the galaxy by simply viewing it in the sky. It wasn't until astronomers mapped out the structure (by 3-d map placement of objects located within it) that it was recognized to have a spiral struture.
Well said, and you're quite right. Since the structure of the galaxy is somewhat of a flat disk, and we're in the disk, we're unable to directly see the arms because we're also in the disk. Part of the mappng process and the determination of spiraled arms has been based on observing areas and alignment of stars more densely grouped in comparison to areas less dense which hels define the arms. We've also been able to take that information and compare it with other galaxies we can see which helps us better visualize what our galaxy looks like. It was only until very recently that the core of the galaxy is not only bulges out from the galactic plane, but that it looks like it's a barred-spiral galaxy rather than a true spiral.

Until, not so long ago, we could guess, but had no real idea what the center of the galaxy looked like because of all dust and gas blocking the view in that direction. However, thanks to improved technologies radio telescopes and x-ray telescopes and infrared telescopes, have given us better information. Using infrared telescopes render the thick clouds of dust and gas nearly invisible leaving the stars themselves to be seen. Being able to look through such dense obstructions has allowed us to determine the path of stars in the center orbiting, at incredible speeds, around an invisible point that must be incredibly dense. That point is thought to be a supermassive black hole. In addition, we're also able to better look inside of dusty stellar nurseries, the remnants of supernovae, to see young stars inside.

While 3-D mapping helps better visualize things, by necessity it's still incomplete in terms full accuracy. We still have no real idea what the opposite side of the galaxy looks like as to the composure of and arms and spurs. There's far too much dust and gas in the galaxy, and we're pushing the limits of current technology just to peek in at the center of it. And there are far too many stars in the galaxy to make an accurate 3-D map. That said, we do have an understanding about spirals, and we can make reasonable and educated guesses as to how the structural parts of the galaxy look. Supercomputers are used to be able to better calculate and plot enormous numbers giving a reasonable estimate about the galaxy's structure, as well as from our observation of other similar galaxies. Even though realistically, it's just an educated guess, it's as close to accurate as we can make at the present time. Perhaps in the future, we'll have the means to be able to more clearly see all of the galaxy.

http://www.uni.edu/morgans/astro/cou...on3/new11.html
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Old 10-31-2011, 10:55 PM
 
3,423 posts, read 3,207,047 times
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Quote:
Originally Posted by NightBazaar View Post
Well said, and you're quite right. Since the structure of the galaxy is somewhat of a flat disk, and we're in the disk, we're unable to directly see the arms because we're also in the disk. Part of the mappng process and the determination of spiraled arms has been based on observing areas and alignment of stars more densely grouped in comparison to areas less dense which hels define the arms. We've also been able to take that information and compare it with other galaxies we can see which helps us better visualize what our galaxy looks like. It was only until very recently that the core of the galaxy is not only bulges out from the galactic plane, but that it looks like it's a barred-spiral galaxy rather than a true spiral.

Until, not so long ago, we could guess, but had no real idea what the center of the galaxy looked like because of all dust and gas blocking the view in that direction. However, thanks to improved technologies radio telescopes and x-ray telescopes and infrared telescopes, have given us better information. Using infrared telescopes render the thick clouds of dust and gas nearly invisible leaving the stars themselves to be seen. Being able to look through such dense obstructions has allowed us to determine the path of stars in the center orbiting, at incredible speeds, around an invisible point that must be incredibly dense. That point is thought to be a supermassive black hole. In addition, we're also able to better look inside of dusty stellar nurseries, the remnants of supernovae, to see young stars inside.

While 3-D mapping helps better visualize things, by necessity it's still incomplete in terms full accuracy. We still have no real idea what the opposite side of the galaxy looks like as to the composure of and arms and spurs. There's far too much dust and gas in the galaxy, and we're pushing the limits of current technology just to peek in at the center of it. And there are far too many stars in the galaxy to make an accurate 3-D map. That said, we do have an understanding about spirals, and we can make reasonable and educated guesses as to how the structural parts of the galaxy look. Supercomputers are used to be able to better calculate and plot enormous numbers giving a reasonable estimate about the galaxy's structure, as well as from our observation of other similar galaxies. Even though realistically, it's just an educated guess, it's as close to accurate as we can make at the present time. Perhaps in the future, we'll have the means to be able to more clearly see all of the galaxy.

Milky Way Galaxy
Within the last week or so, someone (I don't recall who) reported infrared images that saw through a lot of the galaxy's dust and was able to discover two previously unknown globular clusters on the other side of the galaxy. That's quite an acheivement.
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Old 11-01-2011, 10:07 AM
 
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Originally Posted by orogenicman View Post
Within the last week or so, someone (I don't recall who) reported infrared images that saw through a lot of the galaxy's dust and was able to discover two previously unknown globular clusters on the other side of the galaxy. That's quite an acheivement.
You must be talking about this (see links and vid below). I agree, it's a remarkable achievement. The discoveries were made using the VISTA survey telescope in Chile. VISTA has spotted 3 clusters, VVV CL001, VVV CL002, and VVV CL003. The first two are globular clusters, whereas VVV CL003 is an open cluster. If I understand it correctly, VVV CL003 is about 15,000 ly on the other side. VVV CL002 is the closest of it's type to the center of the galaxy. I haven't yet found anything indicating how far the others are estimated to be. As stated in the Universe Today's article (below), "Due the intristic faintness of these new objects, it’s a wonder we can see them at all… In any light!" That's for sure!

As indicated, we've been able to see through the dust and gas to observe the stellar activity around the supermassive black hole at the center from light in the infrared light range, so we should be able to see more beyond the center. Exactly how far is hard to guess. These discoveries may be close to the limits of current technology. Anything farther on the other side of the galaxy (or beyond the galaxy) might require more powerful equipment and creative techniques to detect. I think we'll eventually get there.

I tried to rep you for your post, but I gotta spread it around first. Thanks for mentioning it.

European Telescope Discovers Rare Ancient Star Clusters | Globular Clusters & Milky Way Galaxy | European Southern Observatory & VISTA Telescope | Space.com

Two New Globular Star Clusters Discovered By VISTA

ESO - eso1141 - VISTA Finds New Globular Star Clusters

ESO - eso1141b - VISTA view of the newly discovered globular cluster VVV CL002 close to the centre of the Milky Way

ESO - eso1141a - VISTA view of the newly discovered globular cluster VVV CL001 and its brighter companion



Zoom Into Star Cluster VVV CL001 [720p] - YouTube
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Old 11-01-2011, 11:33 AM
 
Location: Dallas, TX
31,767 posts, read 28,769,662 times
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I would recommend bookmarking APOD. It is not unusual to see details of exposure for such images when they are posted. Here's an example: Eclipse Moon in the Milky Way. This image is mentioned to be a combination of eight consecutive exposures, each 40s long.

PS. To answer the question in the OP...
Quote:
Originally Posted by 6 Foot 3 View Post
O.k. i selelcted this photo off the internet of someone snapping a photo of one of the milky way spiral arms in the night sky and so my question is ..... was the photo possibly a time released shot as i thought that we can't see any of the spiral arms with our naked eye correct?

http://viewzone2.com/milkyway2.jpg
Since the arm we reside is in the same plane as the other arms, we see the dust clouds/arms only with an overlapping perspective, and most of it would be the Orion-Cygnus (minor) arm blocking the view of other arms.

Last edited by EinsteinsGhost; 11-01-2011 at 01:01 PM..
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