Dark Matter or rifts in interstellar clouds?

[spacerings]

http://www.seds.org/messier/m/m024.html<br />The writeup for this photo says that through a chance tunnel in the interstellar dust we can see Messier object 24 which is Sagittarius Star cloud. <br /><br />But when I look at the "Great Rift" in the Milky Way it looks like the same - a tunnel in the dust. Everyone seems to explain it as dark matter or nebulae. <br /><br />Is it really clouds of something dark? Or is it empty areas between the interstellar dust?

 

[newtonian]

spacerings - I thought Sagittarius was a separate galaxy being absorbed by Milky Way?<br /><br />Dark matter is not involved - at least not exotic dark matter.<br /><br />There was a recent Scientific American article concerning recent astronomy seeing though the denser portions of Milky Way.<br /><br />I will try to link to the post I made on this article recently.

 

[newtonian]

two of my posts on the galaxy Sagittarius - 80,000 light years from us, diameter 28,000 light years - within Milky Way:<br /><br />http://uplink.space.com/showthreaded.php?Cat=&Board=sciastro&Number=400131&Search=true&Forum=All_Forums&Words=Sagitarius&Match=Entire%20Phrase&Searchpage=0&Limit=25&Old=1year&Main=398934<br /><br />http://uplink.space.com/showthreaded.php?Cat=&Board=askastronomer&Number=377622&Search=true&Forum=All_Forums&Words=Sagittarius&Match=Entire%20Phrase&Searchpage=0&Limit=25&Old=allposts&Main=373000

 

[harmonicaman]

<b>Spacerings -</b><br /><br />Here's an ADOD item about the "Great Rift" of the Milky Way.<br /><br />The dark band comprising the "Great Rift" of the Milky Way is dust and cosmic debris. It is commonly called Dark Matter merely because it is not illuminated like the stars.<br /><br /><b>Newt -</b><br /><br />Dust in the Milky Way blocks about 25% of our view of the universe. Due to a fortuitous gap or tunnel in this galactic dust, we are able to observe the Sagittarius star cloud! <br /><br />You are confusing the Sagittarius star cloud, M24 (which is a cluster of stars within the Milky Way), with the recently discovered Sagittarius Dwarf Elliptical Galaxy, SagDEG; which is also sometimes confused with the Sagittarius Dwarf Irregular Galaxy, SagDIG.<br /><br />I hope this clears up any confusion you may have... <img src="/images/icons/rolleyes.gif" />

 

[newtonian]

harmonicaman - Thank you - yes I was indeed confusing the two Sagittarius'! <br /><br />Is there a third - i.e. a Sagittarius arm of Milky Way ( and a Perseus arm, etc.)? <br /><br />Did you note the Sciam article which shows this view is now opening up through different methods of observatiions?

 

[harmonicaman]

Here's a chart showing the named arms of the Milky Way. Note that this view is being refined and revised all the time as new and better observations add to our knowledge.

 

[newtonian]

harmonicaman - Thank you again. So there is a Sagittarius arm - I thought so!<br /><br />So, is this mere coincidence that there are 3 Sagittarius'?<br /><br />Or is there some connection - e.g. is the Sagitarrius cloud, M-34 near either the Sagitarrius galaxy or the Sagitarrius arm?

 

[harmonicaman]

The Sagittarius Constellation is in an area of the sky which is full of interesting celestial objects. Sagittarius has fifteen Messier objects, far more than any other constellation.<br /><br />Since everything we see in that part of the sky is associated with "Sagittarius", it gets a bit confusing as to what is what...

 

[newtonian]

harmonicaman - Ah, the signs of the Zodiac.<br /><br />I do not believe in astrology - but then I use the term Thursday and don't worship Thor!<br /><br />And I use the term sunrise though I reject the geocentric universe model!

 

[spacerings]

Thanks Harmonicaman and Newtonian. I finally had a chance to read your responses.

 

[newtonian]

spacerings - You're welcome.