Understanding the Milky Way

[glenc]

What are we looking at when we look at the Milky Way?
How many arms are we looking through when we look in each direction?

Our understanding of the Milky Way has been updated recently.
See: http://www.skyandtelescope.com/news/19599619.html
For more detail see: http://www.nasa.gov/mission_pages/spitzer/multimedia/20080603a.html

When we look towards the center of our galaxy we are looking through 4 arms. The center is 26,000 light years away.
When we look in the other direction we are looking through 3 arms, our arm - the Orion Spur, the Perseus Arm and the Outer Arm.
The edge is 24,000 light years away.

A detailed picture is here:
http://www.nasa.gov/images/content/236084main_MilkyWay-full-annotated.jpg

[renormalised]

...and the Galactic Bar in the middle. Hope they've got beer on tap there, I don't like Romulan Ale:D:P:P:D

[Argonavis]

Thanks for that Glen, you always post interesting stuff.

A brilliant reference to how the appearance of the milky way gives a picture of the architecture of the milky way galaxy is Crossin's Sky Vistas:

http://www.amazon.com/Sky-Vistas-Binoculars-Richest-Field-Telescopes/dp/3211008519/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1214016519&sr=1-1

highly recommended for visual observers.

[glenc]

Thanks Will.

[glenc]

These diagrams shows the nearby nebulae:
http://www.atlasoftheuniverse.com/5000lys.html
http://www.atlasoftheuniverse.com/nebclust.html