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This nebula was discovered by Antoine Darquier de Pellepoix in January, 1779, who reported that it was " large as Jupiter and resembles a planet which is fading." Later the same month, Charles Messier independently found the same nebula while searching for comets. It was then entered into his catalogue as the 57th object. Messier and William Herschel also speculated that the nebula was formed by multiple faint stars that were unable to resolve with his telescope. In 1800, Count Friedrich von Hahn discovered the faint central star in the heart of the nebula. In 1864, William 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. 


Ring Nebula is located in the northern constellation of Lyra, and also catalogued as Messier 57, M57 or NGC 6720. It is one of the most prominent examples of the deep-sky objects called planetary nebulae (singular, planetary nebula), often abbreviated by astronomers as simply planetaries or PNe.

Despite their name, planetary nebulae have nothing to do with planets. They were named originally because their discoverers observed them visually and they did not appear as stellar point sources, but rather as small diffuse objects that resembled the outer planets in our solar system such as Uranus and Neptune when seen in a telescope. Planetary nebula are shells of gas shed by stars late in their life cycles after using up all of their nuclear fuel. The star then ejects a significant portion of its mass in a gaseous shell, which is illuminated by its extremely hot central star, which is just the core left from the original star. The star at the center of the Ring nebula has a surface temperature of 216,000 degrees Farenheit or 120,000 degrees Celsius. Our own star, the Sun, is expected to undergo the same process in a couple of billion years. Planetary nebulae do not last long at all in cosmic terms, the shell of gas expands and diffuses, becoming invisible, and the star turns into a white dwarf. 

Last Updated on Monday, 16 August 2010 13:26