The Ring Nebula, known as M57, is the glowing remnant of a Sun-like star with an apparent magnitude of 8.8. It was discovered in 1779 by the French astronomer Antoine Darquier de Pellepoix. The visible “ring” at the center of this nebula is a thick cylinder of glowing gas and dust surrounding the destroyed star. NASA said that as the star begins to run out of fuel, its core will shrink and heat up, boiling away its outer layers.
The Spitzer telescope detected this nebula using its infrared array camera, showing in detail the outer regions that appear like petals. Spitzer can detect infrared light from hydrogen molecules, which absorb ultraviolet radiation from the star. Earlier images taken by visible-light telescopes usually showed an inner glowing loop of gas around the fading star. The Ring Nebula is an easy target for amateur astronomers because it can be easily observed and is tilted toward Earth.
NASA launched the Spitzer telescope, formerly known as the Space Infrared Telescope Facility, in August 2003. It was closed in January 2020. During the operation, Spitzer discovered a giant ring of Saturn, and revealed a system of seven Earth-sized planets around a star 40 light-years away.