Galactic Plane
The Galactic Plane is the plane in which the majority of a disk-shaped galaxy's mass lies. In the case of the Milky Way, it is the plane of the galaxy's disk, encompassing the spiral arms, stars, gas, and dust. This plane is used as the reference for the galactic coordinate system.
Source: asd.gsfc.nasa.gov
APODs including "Galactic Plane"
A Radio Vista of Cygnus
18/02/2002
Shells of ancient supernovas, cocoons surrounding newborn stars, and specks from distant quasars highlight this tremendous vista toward the constellation of Cygnus. The representative color image covers about 10 degrees across on the sky but is only a small part of the Canadian Galactic Plane Survey in radio light. Diffuse bands of ionized gas flow though a dominating region of star formation, located about 6000 light-years away. Two prominent supernova shells visible include the brown globule on the lower left and the white bumpy sphere on the upper right. To the left of the brown globule is the entire North America Nebula. Prominent stellar cocoons are visible throughout the image as bright white knots. Some of these stars will likely generate future supernova shells. Far in the distance, visible here as only red dots, quasars glow.