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
05/07/2024

A glow from the summit of Mount Etna, famous active stratovolcano of planet Earth, stands out along the horizon in this mountain and night skyscape. Bands of diffuse light from congeries of innumerable stars along the Milky Way galaxy stretch across the sky above. In silhouette, the Milky Way's massive dust clouds are clumped along the galactic plane. Also familiar to northern skygazers are bright stars Deneb, Vega, and Altair, the Summer Triangle straddling dark nebulae and luminous star clouds poised over the volcanic peak. The deep combined exposures reveal the light of active star forming regions along the Milky Way, echoing Etna's ruddy hue in the northern hemisphere summer's night.