M57: The Ring Nebula
Except for the rings of Saturn , the Ring Nebula (M57) is probably the most famous celestial band . Its classic appearance is understood to be due to our own perspective, though. The recent mapping of the expanding nebula's 3-D structure , based in part on this clear Hubble image ,indicates that the nebula is a relatively dense, donut-like ring wrapped around the middle of a (American) football-shaped cloud of glowing gas. The view from planet Earth looks down the long axis of the football, face-on to the ring. Of course, in this well-studied example of a planetary nebula , the glowing material does not come from planets. Instead, the gaseous shroud represents outer layers expelled from the dying, once sun-like star , now a tiny pinprick of light seen at the nebula's center. Intense ultraviolet light from the hot central star ionizes atoms in the gas. The Ring Nebula is about one light-year across and 2,000 light-years away. Share the Sky: NASA Open API for APOD