The Ring Nebula in Lyra is a classic "planetary nebula," the name from William Herschel simply meaning "disk-like." Planetary nebulae are the ejecta dying stars as they turn from giants into white dwarfs. The photograph on the left gives a good sense of how the Ring looks in a small telescope (minus the central star, which is quite difficult to see). It's easily found between Beta and Gamma Lyrae

The distance of the Ring is measured by direct parallax to be 2,300 light years away (accurate to about 40 percent). The angular dimensions of this elliptical object of 86 X 62 seconds of arc (a "second" 1/3600 of a degree) translate to true dimensions of 0.95 X 0.7 light years. The long axis would therefore stretch 20 percent of the way from the Sun to Alpha Centauri. The nebula expanding at a rate of about 30 kilometers per second, is illuminated by the ultralviolet light of the 16th magnitude (15.7) star at the center, which is now a cooling, but still very hot, white dwarf with a temperature of about 150,000 Kelvin and a luminosity some 500 times that of the Sun. Outer shells produced by mass loss in the giant star that created the nebula extend out almost twice as far as seen here, making the whole system nearly two light years across.