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"
The Annotated Galactic Center
27/09/2019
The center of our Milky Way galaxy can be found some 26,000 light-years away toward the constellation Sagittarius. Even on a dark night, you can't really see it though. Gaze in that direction, and your sight-line is quickly obscured by intervening interstellar dust. In fact, dark dust clouds, glowing nebulae, and crowded starfieds are packed along the fertile galactic plane and central regions of our galaxy. This annotated view, a mosaic of dark sky images, highlights some favorites, particularly for small telescope or binocular equipped skygazers. The cropped version puts the direction to the galactic center on the far right. It identifies well-known Messier objects like the Lagoon nebula (M8), the Trifid (M20), star cloud M24, and some of E.E. Barnard's dark markings on the sky. A full version extends the view to the right toward the constellation Scorpius, in all covering over 20 degrees across the center of the Milky Way.