The Earth's home galaxy, the Milky Way, is known as a spiral galaxy because of its shape when viewed face-on. If seen edge-on, the galaxy would appear to be a flat disk-like structure.
At the center of the Milky Way galaxy, there is an extremely bright spot that appears to be a huge star, and a bulge-like region of the galactic disk. Scientists believe that the bright spot is actually a supermassive black hole. Although a black hole is an area of infinite gravity from which not even light can escape, scientists believe that the ring of light is due to matter accelerating and heating up as it revolves around the black hole before crossing its event horizon. The bulging center of the galaxy contains mostly old stars, as well as some dense stellar superclusters that are home to especially exotic and giant stars.
Radiating from the thick middle of a spiral galaxy are several "arms," which resemble the tentacles of an octopus. Current scientific theory explains these galactic arms as the result of density waves passing through the galaxy. The Earth's solar system sits in the Orion arm of the Milky Way, about 25,000 light-years from the galactic center.