Fr.: plan galactique
The plane in which the → disk of a → spiral galaxy, such as our → Milky Way, lies.
Fr.: plan supergalactique
The symmetry plane of the → Local Supercluster, where density of galaxies in our environment is the largest. The plane passes through the → Virgo cluster of galaxies, about which many of the brightest galaxies in the sky are concentrated. The supergalactic plane was recognized by Gérard de Vaucouleurs (1918-1995) in 1953 from the → Shapley-Ames catalogue.
→ supergalactic; → plane.