The Ring Nebula (M57) is a famous planetary nebula located in the constellation Lyra, approximately 2,300 light-years away from Earth. It has a distinct, donut-like appearance due to its structure: a glowing shell of ionized gas ejected by a dying star. The nebula's central star, a white dwarf, is the remnant of the original star, which has shed its outer layers. The nebula is about 1 light-year in diameter, and its striking shape and colorful appearance, with hues of green, blue, and red, make it a popular target for both amateur and professional astronomers.