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perchance
2011-Feb-26, 03:53 PM
Hello everyone, I am brand new to astronomy, and even newer to your board.

Here is my first dumb question: I ordered a poster / photograph of the Milky Way, it looks to be a photo of the entire galaxy from space, will I be getting a true photo or a artist conception of what we believe the Milky Way looks like? In other words can we see our own galaxy in its entirety?

Thank you, Chance

PetersCreek
2011-Feb-26, 06:25 PM
In other words can we see our own galaxy in its entirety?

Nope. Since we live inside our galaxy and have no means of traveling outside of it to take a photograph, all that's available are artists' conceptions and computer generated images.

And now, a friendly note from one of your moderators:

Welcome to the BAUT forums. Things work a little differently here than on other boards, so please take a few minutes to read our rules, posted in my signature line below. I hope you enjoy your time here.

ngc3314
2011-Feb-26, 08:41 PM
On the other hand, we are so far out in the disk of the Milky Way that an all-sky image wrapped around in map projection can give a surprisingly outside-looking view. Examples include the famous COBE infrared image (http://apod.nasa.gov/apod/image/cobe_milkyw.gif), assisted by a high-contrast display, a higher-range display from COBE data (http://apod.nasa.gov/apod/image/0001/milkyway_cobe_big.jpg), the near-IR 2MASS view (http://www.ipac.caltech.edu/2mass/gallery/showcase/allsky_stars/enlarged.html), and in the optical, Axel Mellinger's absolutely fantastic mosaic image (http://home.arcor-online.de/axel.mellinger/). Comparing these shows what a toll interstellar dust takes on the visible-light structure of the Milky Way.

forrest noble
2011-Feb-26, 10:48 PM
My guess is that you will get a picture of another similar galaxy, retouched to match the details presently believed to exist in the Milky Way from that perspective. That's what I would do if I were selling, or sending out such pictures. As to your question, inside the Milky Way we can take no pictures of the whole of it as you would see from outside its confines.

By the way "perchance", welcome to BAUT on your very first posting :)

Jens
2011-Feb-27, 05:01 AM
Here is my first dumb question: I ordered a poster / photograph of the Milky Way, it looks to be a photo of the entire galaxy from space, will I be getting a true photo or a artist conception of what we believe the Milky Way looks like? In other words can we see our own galaxy in its entirety?


If the company really said it was a photo, then I think they would be guilty of false advertising. A picture is OK, but even then, we really aren't completely certain of what the Milky Way would look like. Recently it has become suspected that the MW is a barred spiral, as in this illustration (http://apod.nasa.gov/apod/ap050825.html).

Tobin Dax
2011-Feb-27, 05:26 AM
My guess is that you will get a picture of another similar galaxy, retouched to match the details presently believed to exist in the Milky Way from that perspective. That's what I would do if I were selling, or sending out such pictures.

"Retouching" another galaxy sounds like a lot of work. I suspect that the poster is the image Jens linked to.

Peter B
2011-Feb-27, 09:20 AM
Hello everyone, I am brand new to astronomy, and even newer to your board.

Here is my first dumb question: I ordered a poster / photograph of the Milky Way, it looks to be a photo of the entire galaxy from space, will I be getting a true photo or a artist conception of what we believe the Milky Way looks like? In other words can we see our own galaxy in its entirety?

Thank you, Chance

G'day (per)Chance, and welcome to the BAUT Forum.

While the other people who've responded in this thread have given you the correct answer, I'd like to explain why those answers are correct.

We can only take images in space using spacecraft we've sent out. The furthest any of our spacecraft have travelled from Earth is less than 0.002 light years (that's Voyager 1). As the nearest star to the Sun is more than 4 light years away, and as our galaxy is more than 100,000 light years across, our spacecraft haven't even come close to leaving the galaxy.

To put it in scale, imagine the Milky Way galaxy was 10 metres across (say, the size of a small apartment). At that scale, 1 millimetre would be equivalent to 10 light years. Voyager 1 would have travelled 0.0002 millimetres, which is less than the diameter of the finest hair.

antoniseb
2011-Feb-27, 03:59 PM
... will I be getting a true photo or a artist conception of what we believe the Milky Way looks like? ...
There are good answers from everyone. I'm asking that when you do get it, you tell us what you got.
It could be a Milky Way panorama from our point of view. It could be a computer generated view as seen from outside. It could be artwork (I think from your description, that's the least likely)... but whatever it is, you've got most of us curious.

forrest noble
2011-Feb-27, 07:53 PM
"Retouching" another galaxy sounds like a lot of work. I suspect that the poster is the image Jens linked to.

Your are probably right, just another similar looking galaxy (hopefully telling which galaxy it really is). My version if I were doing the retouching, I think could be done by hand or with photo shop in just a day or so, however :) . From the last that I read maybe last week, our galaxy is presently thought (at least by the authors of the paper) to be primarily a four armed spiral.

Tobin Dax
2011-Feb-28, 02:11 AM
Your are probably right, just another similar looking galaxy (hopefully telling which galaxy it really is).

For the record, that is not what I said. This (http://www.spitzer.caltech.edu/images/1927-ssc2008-10a1-The-Milky-Way-Galaxy) picture is not a modified picture of another galaxy as far as I can tell, and I have never heard it described as such.


perchance, as antoniseb said, I hope you'll share with us what your poster is. I'm one of the "most of us" he refers to. :)

forrest noble
2011-Feb-28, 05:24 AM
For the record, that is not what I said. This (http://www.spitzer.caltech.edu/images/1927-ssc2008-10a1-The-Milky-Way-Galaxy) picture is not a modified picture of another galaxy as far as I can tell, and I have never heard it described as such.

perchance, as antoniseb said, I hope you'll share with us what your poster is. I'm one of the "most of us" he refers to. :)

You misunderstood me. By my statement I was agreeing with you that the picture they will be sending him will probably be just a picture of a similar looking galaxy (untouched). And added that hopefully they will identify which one that it is.

Jens
2011-Feb-28, 05:45 AM
You misunderstood me. By my statement I was agreeing with you that the picture they will be sending him will probably be just a picture of a similar looking galaxy (untouched). And added that hopefully they will identify which one that it is.

I don't think it's a big deal one way or the other, but what Tobin Dax is trying to get across is that he was not saying that it would be an untouched picture of a similar galaxy, so you aren't really agreeing with him. I think he was agreeing with me that it's probably an artist's illustration (as in the picture I linked to).

astromark
2011-Feb-28, 07:13 AM
Have we lost this new post er.. ? Has he returned to read the answers provided.. ?
The poster he has purchased will be one of the two mentioned above... nether of them are what he wants
( I can not know that ) One being a actual compilation of hundreds of actual images to build a image of the view we have of the whole sky... That being a composite image of the Milky Way. The other is clearly a work of art. Depicting the shape of this galaxy from a right angle view... as best as we can judge. Or there is a third possible image to purchase...
That being the cosmological whole of the Universe image.. which oddly enough is also a work of art... compiled from radio telescope images of what we think we can detect... are you still here Perchance ?

Jens
2011-Feb-28, 07:20 AM
The poster he has purchased will be one of the two mentioned above... nether of them are what he wants
( I can not know that )

You say "neither of them are what he wants" but also "I cannot know that." If you can't know that, then why can you assert that? :)

Tobin Dax
2011-Feb-28, 07:38 AM
I don't think it's a big deal one way or the other, but what Tobin Dax is trying to get across is that he was not saying that it would be an untouched picture of a similar galaxy, so you aren't really agreeing with him. I think he was agreeing with me that it's probably an artist's illustration (as in the picture I linked to).

Jens understands and is correct on all points.

astromark
2011-Feb-28, 09:34 AM
You say "neither of them are what he wants" but also "I cannot know that." If you can't know that, then why can you assert that? :)

OK, So i spell neither wrong. I made my point. Which you missed. I do not pretend to know the minds of others...
I am sure you did read the OP.. and you did understand me.. replace assert with suggest. I would not assert anything.

Hullo Perchance., are you there ? Look what you've done....

Earth calling perchance... are you here ?

kzb
2011-Mar-03, 06:35 PM
I suspect the image may be this, which comes from NASA and got wide circulation a few months back. It is available from this site amongst others:

http://www.spitzer.caltech.edu/search/image_set/20?search=sig05-010

It is an artist's impression, and personally I don't really like it. It looks too artificial, with its overly straight, bright bar. I also believe some scientists in the field have "issues" with its accuracy: even the number of spiral arms is controversial.

Somewhere I have a paper which goes into some depth on which other galaxies the MW most resembles from outside. None of them look much like that NASA picture I can tell you. I'll try and find the link to the arxiv paper later.

grapes
2011-Mar-03, 06:53 PM
I suspect the image may be this, which comes from NASA and got wide circulation a few months back. It is available from this site amongst others:

http://www.spitzer.caltech.edu/search/image_set/20?search=sig05-010Ooo, pretty. But there's a link there to a "significantly updated view of our Milky Way galaxy" here: A Roadmap to the Milky Way (http://www.spitzer.caltech.edu/images/1923)

eburacum45
2011-Mar-04, 10:19 AM
An annotated version is available here
http://www.nasa.gov/mission_pages/spitzer/multimedia/20080603a.html

however this is still not the definitive Milky Way map; this image by Diana Marques seem to show the Orion Spur splitting into two, with one spur extending into, and interacting with the Perseus Arm - see here
http://galaxymap.org/book_images/orientation/orion_spur.jpg

another interesting map here, showing the locations of many significant nebulae and other objects, and the disposition of the non-ionised hydrogen clouds;
http://galaxymap.org/perturbed1280x1024.png
this seems to broadly agree with the Diana Marques map.

all from this fascinating site
http://galaxymap.org/

kzb
2011-Mar-04, 12:52 PM
On the Spiral Structure of the Milky Way Galaxy Yu N Efremov (2010) (link below). This paper contends that the MW looks most like the galaxies listed here:

NGC 3124 see
http://www.skyfactory.org/deepskycatalogue/NGC3124.html

NGC 3992 also called M109
see http://en.wikipedia.org/wiki/Messier_109

NGC 2336 see
http://www.noao.edu/outreach/aop/observers/n2336.html

Link to article:
http://arxiv.org/ftp/arxiv/papers/1011/1011.4576.pdf

eburacum45 and grapes: not sure how this paper stands in relation to the "significantly updated roadmap" linked to by grapes. However at first sight you've got to say these galaxies look very similar to that.

I was thinking last night though: if you were looking out the portholes in your warp-drive starship hovering 15kpc above the centre of the MW, what would you actually see with the unaided eye? Not much is my bet. After all we need good seeing conditions and low light pollution to make out the Mikly Way at all, and we are sat in the middle of the disk.