Encyclopædia Galactica Rami T. F. Rekola Tuorlan Astronomical Society Tuorla Observatory University of Turku

Supergalactic Plane

The grand old man of galaxy research, Gérard de Vaucouleurs, noticed that when you plot all nearby galaxies in a 3D plot, they lie more or less on a plane (with a certain thickness, of course). He based a new coordinate system, the supergalactic coordinate system, on this plane. The Earth is at the origin of this coordinate system and, hence, the supergalactic plane passes through the Earth.

Objects with supergalactic latitude (SGB) at zero degrees lie on the supergalactic plane. Another variant of the coordinate system is supergalactic cartesian coordinate system, with positions of objects given with cartesian coordinates SGX, SGY and SGZ. The supergalactic plane is the same as the SGX-SGY -plane. Hence objects that lie on the supergalactic plane have SGZ value of zero.