The word galaxy is derived from the greek word for milk, and hence our Galaxy is named the Milky Way system. Group of stars are called galaxies. Our star, the Sun, belongs to a system called The Milky Way Galaxy. The Milky Way can be seen as a band of stars in the night sky. The Milky Way is basically a disk of stars with a large central bulge. The central bulge contains the galactic nucleus. The band of light associated with the Milky Way is comprised of stars and is actually our view of the galactic disk from a vantage point more or less in the mid-plane of the disk. The Milky Way Galaxy is a vast pinwheel of stars and gas turning within an enormous cloud of invisible matter. Many generations of stars have formed and died within its disk, enriching our galaxy’s stock of heavy elements. Before the disk formed, the future Milky Way probably existed as several distinct galaxies which fell together and merged.