The Milky Way's Many Faces

[@MDSBock]

Well done on a comprehensive explanation on the different views of the Milky Way n spiral galaxies, I really enjoyed it.

[@JasonKendallAstronomer]

Glad you enjoyed it!

[@hank1519]

Great job, Jason!

[@warpdriveby]

Does the pattern of light and dark patches truly "never" change? With the fact that star velocity is not strongly tied to distance and that they also orbit each other, stars like the Sun take pretty complex "paths" around the core. It would have to change over tens of millions of years right?

[@JasonKendallAstronomer]

That’s correct. It would take that long. But then the change would be folded in with the Sun’s motion around the Galaxy, and the cloud’s evolution through Star formation.

[@warpdriveby]

@@JasonKendallAstronomer Awesome, Thank you for answering! I haven't found an answer to another question, so hopefully you know it, if I could ask for it, please? Here goes: How stable is the Sun's orbit of the galactic centre of mass, both in inclination to the galactic disk, and in the severity of it's elliptical shape? I see the statement: "The sun moves up and down through the galactic disk as it orbits" as if it would look like a loop of sine waves. I had thought it meant the Sun's path was analogous to Pluto's, to grossly oversimplify. What would one or two orbits look like if drawn over a top down, and an edge on view of the galaxy?

[@hank1519]

Jason, when did we discover that there are galaxies outside of our own?

[@JasonKendallAstronomer]

Well, it can be thought that the "Spiral Nebulae" that the Earl of Rosse found with his big scope could be thought of as that. However, we could have also thought that Charles Messier and his contemporaries could think that. But the real discovery that Things Are Far comes from Edwin Hubble's discovery of Cepheids in M31 in 1923. That's the subject of my recent blast of videos: "The Great Distance Problem" I go through the whole history. look here: kzbin.info/www/bejne/ZoOcYqqGlpd7e6M

[@hank1519]

Jason Kendall Thanks for your answer and the link!

[@jdsgotninelives]

We are losing the battle with light pollution :-(

[@JasonKendallAstronomer]

Once I am done with the standard intro course, I intend to tackle light pollution as a channel topic.