M57, the Ring Nebula, is probably the finest example of a planetary nebula anywhere in the sky. It was formed when a star about the size of the Sun neared the end of its life cycle and shed its outer shell of hydrogen gas. This shell of material is illuminated by the remains of the star, known as a white dwarf, in the center. The nebula is well-known for its beautiful colors, ranging from red to yellow, green, and blue. Its age is estimated at about 5,500 years. Its distance from Earth is not very well known.