The Ring Nebula (also catalogued as Messier 57, M57 and NGC 6720) is a planetary nebula in the northern constellation of Lyra. Such a 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.
M57 is 2,570 light-years from Earth. It has a visual magnitude of 8.8 and a dimmer photographic magnitude, of 9.7. Photographs taken over a period of 50 years show the rate of nebula expansion is roughly 1 arcsecond per century, which corresponds to spectroscopic observations as 20–30 km s−1. M57 is illuminated by a central white dwarf or planetary nebula nucleus (PNN) of 15.75v visual magnitude.

M57, Ring nebula
Photographed with APO107 refractor and Atik 360EX CCD monochrome camera in Stuvsta September 2019. Exposure was 20 min with each of LRGB filters.

M57, Ring nebula
Photographed with APO107 refractor and Nikon D800 camera in Stuvsta September 2016. Exposure was 9*30s.

M57, Ring nebula
An early attempt photographed with CPC925 reflector telescope and Nikon D800 camera in Stuvsta, September 2015.

M57, Ring nebula
Photographed with APO107 refractor telescope and ASI 2600MC color camera in Stuvsta, August 2021. Exposure was 8*3min.

M57, Ring nebula
Photographed with APO107 refractor telescope and Nikon D800 camera in Åva October 2016. 12 min exposure.