ⓘ Fundamental plane, spherical coordinates. The fundamental plane in a spherical coordinate system is a plane of reference that divides the sphere into two hemisp ..

                                     

ⓘ Fundamental plane (spherical coordinates)

The fundamental plane in a spherical coordinate system is a plane of reference that divides the sphere into two hemispheres. The geocentric latitude of a point is then the angle between the fundamental plane and the line joining the point to the centre of the sphere.

For a geographic coordinate system of the Earth, the fundamental plane is the Equator. Celestial coordinate systems have varying fundamental planes:

  • The galactic coordinate system uses the Milky Ways galactic equator.
  • The Besselian coordinate system uses Earths terminator day/night boundary. This is a Cartesian coordinate system x, y, z.
  • The horizontal coordinate system uses the observers horizon.
  • The ecliptic coordinate system uses the ecliptic.
  • The equatorial coordinate system uses the celestial equator.