This nebula was discovered by the French astronomer Charles Messier while searching for comets in late January 1779. Messier's report of his independent discovery of Comet Bode reached fellow French astronomer Antoine Darquier de Pellepoix two weeks later, who then independently rediscovered the nebula while following the comet. Darquier later reported that it was "...as large as Jupiter and resembles a planet which is fading" (which may have contributed to the use of the persistent "planetary nebula" terminology).[5] It would be entered into Messier's catalogue as the 57th object. Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope.[6][7]In 1800, German Count Friedrich von Hahn announced that he had discovered the faint central star at the heart of the nebula a few years earlier. He also noted that the interior of the ring had undergone changes, and said he could no longer find the central star.[8] In 1864, English amateur astronomerWilliam Huggins examined the spectra of multiple nebulae, discovering that some of these objects, including M57, displayed the spectra of bright emission lines characteristic of fluorescing glowing gases. Huggins concluded that most planetary nebulae were not composed of unresolved stars, as had been previously suspected, but were nebulosities.[9][10] The nebula was first photographed by the Hungarian astronomer Eugene von Gothard in 1886.[8]Observation
Location of M57 in the constellation LyraMessier 57 is found south of the bright star Vega, which forms the northwestern vertex of the Summer Triangle asterism. The nebula lies about 40% of the distance from Beta (β) to Gamma (γ) Lyrae, making it an easy target for amateur astronomers to find.[11]The nebula disk has an angular size of 1.5 × 1 arcminutes, making it too small to be resolved with 10×50 binoculars.[11] It is best observed using a telescope with an aperture of at least 20 cm (8 in), but even a 7.5 cm (3 in) telescope will reveal its elliptical ring shape.[12] Using a UHC or OIII filter greatly enhances visual observation, particularly in light polluted areas. The interior hole can be resolved by a 10 cm (4 in) instrument at a magnification of 100×.[11] Larger instruments will show a few darker zones on the eastern and western edges of the ring, and some faint nebulosity inside the disk.[13] The central star, at magnitude 14.8, is difficult to spot.[12]