The Andromeda Galaxy (M31) ~ A massive spiral 2.5 million light-years away, over twice the diameter of our own Milky Way, it's the largest nearby galaxy. Andromeda's population of bright young blue stars lie along its sweeping spiral arms. (Spitzer Space Telescope)
Hoag's Object is a mysterious ring galaxy 600 million light years awayin the constellation Serpens. The outer ring is composed largely of hotblue stars, while the core is older red and yellow stars. The space inbetween is almost completely dark. It is thought that this galaxyformed from the collision of two galaxies billions of years ago.Visible near the top of the gap is another ring galaxy, likely muchfurther away.