The Ring nebula (M57) in Lyra. This is in the class of objects known as planetary nebula. Actually a shell of gas and not a ring, it is thought to be the result of ejection of gas from the central star. Located about 1800 light years away, the ring or shell is 0.5 light years in diameter. The expansion rate is a relatively slow 12 miles/sec. which indicates that the ejection occured about 20,000 years ago.