In geometry, a coordinate system in which any point in three-dimensional space is specified by its angle with respect to a polar axis and angle of rotation with respect to a prime meridian on a sphere of a given radius.
In spherical coordinates a point is specified by the triplet (r, 03B8; , 03C6; ), where r is the point's distance from the origin (the radius), 03B8; is the angle of rotation from the initial meridian plane, and 03C6; is the angle from the polar axis (analogous to a ray from the origin through the North Pole).