Galactic coordinate

A galactic coordinate, in stellar cartography, galactic latitude or longitude. The two coordinates constitute a useful means of locating the relative positions and motions of components of the Milky Way Galaxy. Galactic latitude (denoted by the symbol b) is measured in degrees north or south of the Galaxy’s fundamental plane of symmetry. This plane is defined by the galactic equator, the great circle in the sky best fitting the plane of the Milky Way, as determined by a combination of optical and radio measurements.