Galactic coordinate system

The galactic coordinate system is a celestial coordinate system that uses the Milky Way as its fundamental plane[?]. The latitudinal angle is called the galactic latitude[?], and the longitudinal angle is called the galactic longitude[?]. This coordinate system is useful for studying the galaxy itself. For example, you might want to know how the density of stars changes as a function of galactic latitude, to how much the disk of the Milky Way is flattened.