Ring Nebula

The Ring Nebula is a planetary nebula in the northern constellation of Lyra, about mid-way between the prominent stars Beta and Gamma Lyrae. It is also catalogued as Messier 57, M57 and NGC 6720. The nebula was discovered by Charles Messier in 1779. It has an apparent visual magnitude of 8.8, which is too faint to be visible with the naked eye, but it can be readily observed with a small telescope. A planetary nebula is formed when a star, during the last stages of its evolution before becoming a white dwarf, expels a vast luminous envelope of ionized gas into the surrounding interstellar space. The progenitor star for the ring nebula is now a carbon-oxygen white dwarf with an apparent visual magnitude of +15.75. Based on parallax measurements, this star is located at a distance of approximately 2,570 light-years (790 pc) from the Sun. After expanding for 1,610 years, the nebula currently has a diameter of 1 ly.