                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2021 August 17

                      M57: The Ring Nebula from Hubble
      Image Credit: NASA, ESA, Hubble Legacy Archive; Processing: Judy
                                   Schmidt

   Explanation: Except for the rings of Saturn, the Ring Nebula (M57) is
   probably the most famous celestial circle. 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 2,500 light-years away.

    Share the Sky: NASA Open API for APOD Tomorrow's picture: rings upon
                                    Ring
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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