The Ring Nebula (M57) is probably the most famous celestial band, other than the rings of Saturn. Its classic appearance is understood to be due to perspective - our view from planet Earth looks down the center of a roughly barrel-shaped cloud of glowing gas. Of course, in this well-studied example of a planetary nebula, the glowing material does not come from planets. Instead, the gaseous atmosphere represents outer layers expelled from the once sun-like star at the nebula's center. The central ring of the Ring Nebula is about one light-year across and 2,000 light-years away. To accompany tonight's shooting stars it shines in the northen constellation Lyra.
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