Four views of the Ring Nebula, M57

The Ring Nebula, Messier object 57 (M57), NGC 6720, in the constellation Lyra. This image shows four different views of the nebula as seen at four different wavelengths (colors of light). The use of multi-color imaging helps to reveal physical conditions in the nebula, as different colors of light are emitted by different gases in varying physical states. These pictures were taken with the Kitt Peak 2.1-meter telescope in 1973, using the 40cm Carnegie image tube and an enhanced two inch photographic plate, by Dr Larry Goad. M57 was the first of the class called planetary nebulae to be discovered. It is about 3000 light-years away and about a light-year across.