This false-colour Hubble Space Telescope image is of the Ring Nebula, 2,000 light years away. The Ring is a planetary nebula, a Sun-like star in the late stages of evolution. As they die, Sun-like stars swell to become red giants before ejecting their outer layers. What remains is a small star that will become a white dwarf, within a shell of glowing gas expanding at about 20 kilometers per second. The type of stellar outburst determines the nebula's shape; in the Ring Nebula it is barrel-like and less than a light-year across. Intense radiation from the central while dwarf causes the gas in the shell to glow.