Categories: Articles to be expanded | Astronomy stubs | Galaxy stubs | Galaxies In astrophysics, the questions of galaxy formation and evolution are: How, from a homogeneous universe, did we obtain the very inhomogeneous one we live in? How did galaxies form? How do galaxies change over time? The formation of galaxies is still one of the most active research areas in astrophysics... Many galaxies, including the Milky Way in which our Sun and Earth are located, are disk-shaped: the majority of their visible mass (excluding possible dark matter) lies very close to a plane. ... In astronomy, a bulge is a huge, tightly packed group of stars. ... It has been suggested that galaxy halo be merged into this article or section. ... The Structure of the Galaxy The galactic corona (not to be confused with the suns corona; also called the dark matter halo) is a region of space surrounding the galactic halo of spiral galaxies, including the Milky Way Galaxy that consist mostly of dark matter. ...