Disk vs. Halo Orbits
				– The Disk Component • Stars, gas, and dust – The spiral arms • Size: – Luminous Diameter ~ 25 kpc – Thickness 300 pc – 1 kpc O stars and dust smaller Sun-like stars greater – The Spherical Component • Old Stars, but little gas or dust • The Halo – Globular clusters – Isolated old stars » red dwarfs, giants, white dwarfs • The Nuclear Bulge