photos of Milky Way galaxy

[spacerings]

I honestly don't know or I wouldn't ask. Do we have photos of the Milky way galaxy where you can see the whole thing? I've seen spiral galaxies like Andromeda. Have we gotten far out enought for this?

 

[nevers]

Nope, but it never hurts to ask. We've barely reached beyond our own Solar System and communication was lost. I found this picture that shows how our Galaxy would be perceived from a distance away.

 

[spacerings]

Thank you Brad. It's great there's a place I can ask my questions like this. -C

 

[tplank]

Very cool graphic. Which raises a question: how confident are we in the structure of our galaxy on the other side of the center? Obviously, we do not observe it directly. Seems like many possibilities. If I was an alien, that is how I would sneak up on us-by diving down from the sun's direction. :-D <div class="Discussion_UserSignature"> <p>The Disenfranchised Curmudgeon</p><p>http://tonyplank.blogspot.com/ </p> </div>

 

[jcdenton]

We know the Milky Way is a spiral galaxy, and those have a fairly uniform structure. <div class="Discussion_UserSignature"> </div>

 

[harmonicaman]

Some pesky revisionist astronomers are now saying the Milky Way Galaxy should be reclassified as a barred (SB) or barred spiral galaxy (SAB); rather than a pure spiral (Sb or Sbc).<br /><br />A lot more measurements are needed before our classification will be officially changed though...<br /><br />Another outside view of the Milky Way... <img src="/images/icons/rolleyes.gif" /><br /><br />

 

[tplank]

jcdenton,<br /><br />Well, that just pushes the problem back a step. I'm not doubting that it is a sprial galaxy. I'm just musing about what led people to that conclusion.<br /><br />To be a little more pointed at the risk of exposing my profound ignorance...I know that we have learned some of the structural detail because of the gravitational lens which is the center of our galaxy. I assume that much of this data is in non-visible parts of the electomagetic spectrum. I'm assuming there is data collected which suggests the structure that we "can't see". I'm just wondering how conclusive that is and the nature of the data. <div class="Discussion_UserSignature"> <p>The Disenfranchised Curmudgeon</p><p>http://tonyplank.blogspot.com/ </p> </div>

 

[CalliArcale]

The galaxy is definitely observed in a number of wavelengths; infrared in particular is very useful for penetrating the dust lanes. There is a great deal of it that cannot be detected from here, though. Scientists have extrapolated the likely shape of the Milky Way from careful observing of various stars and other objects and their actual motion relative to the galaxy, and by comparing the Milky Way to other galaxies that seem to be similar in size and age. But the exact appearance is really a guess, as you've surmised. Recently, some astronomers have started suggesting that the Milky Way is a barred spiral, which is a change from the previous consensus that it was probably a more regular spiral. As observations improve, it is likely that astronomers will refine the predicted shape of the galaxy.<br /><br />I suppose it's a bit like early cartography. Map-makers made their best guess as to what the Earth looked like, based on the best reports available. Some were more accurate than others. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[tplank]

Thanks Callie for the response.<br /><br />I guess I have been seeing that "you are here" picture for probably at least twenty years and it has always made me think. I have also paid attention to all the galactic collision talk and what strikes me about those is the unusual shapes that get created... hard not to wonder what is on the other side of the trees in our forest.<br /><br />Maybe I should be an astrocartographer when I grow up. <div class="Discussion_UserSignature"> <p>The Disenfranchised Curmudgeon</p><p>http://tonyplank.blogspot.com/ </p> </div>

 

[formulaterp]

<font color="yellow">hard not to wonder what is on the other side of the trees in our forest</font><br /><br />Indeed. Consider that astronomers have known about small companion galaxies to the Milky Way for ages, such as the Magellenic Clouds. Turns out there is another dwarf galaxy which is even closer to us, but it resides on almost exactly the opposite side of the MW. Now known as the Saggitarius Dwarf Elliptical Galaxy (SagDEG), it wasn't identified until 1994.

 

[tplank]

If it isn't a lot of trouble to answer, how did they identify SagDEG? <div class="Discussion_UserSignature"> <p>The Disenfranchised Curmudgeon</p><p>http://tonyplank.blogspot.com/ </p> </div>

 

[formulaterp]

Well basically astronomers looked at the central bulge of the Milky Way and identified certain stars whose movements were inconsistent with being a part of the MW. This clue helped them to identify a large cluster of stars whose common motion indicated that they were members of what would be later identified as SagDEG. Additional observations have located a trailing stream of stars which have been ripped from SagDEG, nearly forming a ring around the galaxy. <br /><br />A great page on SagDEG can be found here:<br /><br />http://www.solstation.com/x-objects/sag-deg.htm

 

[tplank]

formulaterp,<br /><br />Thanks for that link...that is awesome stuff. Very interesting. Anybody who has not checked it out definitely should! <div class="Discussion_UserSignature"> <p>The Disenfranchised Curmudgeon</p><p>http://tonyplank.blogspot.com/ </p> </div>

 

[tplank]

Steve,<br /><br />Interesting stuff. Thanks for the info. If you want to drum up a trip to the Large Magellanic Cloud, I’ll chip in on the deposit for the charter. <img src="/images/icons/wink.gif" /><br /> <div class="Discussion_UserSignature"> <p>The Disenfranchised Curmudgeon</p><p>http://tonyplank.blogspot.com/ </p> </div>

 

[bobw]

The picture shows the trail of debris left as SagDEG travels in it's billion year polar orbit, 50,000 ly from the center of the Milky Way; not the galaxy itself. It is on the other side of the core now but 250,000 million years ago it would have been pretty easy to spot. I thought the illustration was OK. I suppose the relative brightness of the ring was exaggerated a bit, if that's what you meant. You don't dispute the polar orbit part, do you? <div class="Discussion_UserSignature"> </div>