Coordinate System

A method using Great circles to provide a means to specify a unique location on the celestial sphere, such as Horizon (altitude and azimuth) Celestial Equator (right ascension and declination) Ecliptic (celestial latitude and celestial longitude) The most important system of coordinates for general mathematical purposes is Cartesian coordinates, which locates points in terms of their distances from certain coordinate axes in much the same way that a city map fixes places by the intersection of numbered streets and avenues. Spherical coordinates use great circles on the surface of a sphere as reference lines just as we use longitude and latitude to fix places on a globe. The longitude and latitude and difference from a fixed center serve to locate a point in three dimensional space. Spherical coordinates are especially useful in astronomy and astrology.