M57

The Ring Nebula is one of the best-known planetary nebulae in the sky, located about 2,283 light-years away in the constellation Lyra. Despite its name, it has nothing to do with planets — the term was coined by William Herschel because these nebulae resembled the disks of planets through early telescopes. The Ring is a shell of ionized gas expelled by a dying sun-like star roughly 4,000 years ago. The central star, a hot white dwarf with a surface temperature of about 120,000 K, illuminates the expanding shell.

Easy to locate between Beta and Gamma Lyrae (the two bottom stars of the Lyra parallelogram). At low power it appears as a slightly fuzzy star. At 100x or more in a 4-inch telescope, the ring shape becomes clearly visible — a small, bright smoke ring floating in space. The central hole is easier to see with averted vision. The central star requires at least a 12-inch telescope under excellent conditions. An OIII filter enhances contrast against the sky background. Best observed from June through November when Lyra is high overhead.

Discovered by Antoine Darquier de Pellepoix in January 1779, who described it as 'a very dull nebula, but perfectly outlined; as large as Jupiter and looks like a fading planet.' Charles Messier independently found it later the same month and added it to his catalog. In the 19th century, spectroscopy revealed its gaseous nature, and it became a prototype for understanding how sun-like stars end their lives.