Messier 57, the Ring Nebula, is one of the most famous examples of a planetary nebula.

Located 2,300 light-years away in the constellation of Lyra, it has an apparent diameter of 98 x 80 arcseconds and a real diameter of one light-year in space.

At magnitude 8.8 its high surface brightness makes it an easy target for observation, even from metropolitan areas compromised by light pollution, and even with small telescopes.

The central star that illuminates the Ring nebula, however, is a legendary observing challenge for amateur astronomers. It shines at magnitude 15.3. It usually takes a fairly large-aperture scope under great seeing conditions to see it. It has a surface temperature of 216,000 degrees Fahrenheit or 120,000 degrees Celsius.

As noted by astronomer and observer Brian Skiff, the two faint stars just outside of the Ring Nebula, at magnitudes 14.1 and 14.7 must first be visible if any hope of seeing the central star is to be realized.

In a large telescope the central portion of the doughnut of M57 is bright with nebulosity, making the detection of the central star much more difficult than if it were isolated against a black sky background.

In addition to a large-aperture high-optical-quality telescope (12 inches or larger), high magnification (500x), good transparency, great seeing (usually one arc-second or better), and considerable observing skill are necessary to see this star. Very large telescopes will reveal the central star under less than perfect conditions.

A second star may also be seen inside of the Ring with very large telescopes. It has a magnitude of approximately 16.25 and is located 10 arcseconds to the northwest of the central star.

The Ring Nebula was discovered by Antoine Darquier de Pellepoix in January of 1779.

North is to the top in the above image.

Messier 57 Catalogs: M57, NGC 6720, PK 063+13.1 Common Name: Ring Nebula Object Type: Planetary Nebula Magnitude: 8.8v Size: 98" x 80" Constellation: Lyra Image Field Centered At: RA: 18h 53m 34s Dec: +33° 01' 35"