An Etymological Dictionary of Astronomy and Astrophysics

A bright → planetary nebula in the constellation
→ Lyra, also called M57 or NGC 6720.
In small telescopes it has the appearance of a slightly elliptical luminous ring around a central hot star (15th magnitude). The radius is one-third of a → light-year, and the nebula is about 2,000 light-years away.

See also: → ring; → nebula.