                        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.

                               2020 August 23

                   The Helix Nebula from Blanco and Hubble
       Image Credit: C. R. O'Dell, (Vanderbilt) et al. ESA, NOAO, NASA

   Explanation: How did a star create the Helix nebula? The shapes of
   planetary nebula like the Helix are important because they likely hold
   clues to how stars like the Sun end their lives. Observations by the
   orbiting Hubble Space Telescope and the 4-meter Blanco Telescope in
   Chile, however, have shown the Helix is not really a simple helix.
   Rather, it incorporates two nearly perpendicular disks as well as arcs,
   shocks, and even features not well understood. Even so, many strikingly
   geometric symmetries remain. How a single Sun-like star created such
   beautiful yet geometric complexity is a topic of research. The Helix
   Nebula is the nearest planetary nebula to Earth, lies only about 700
   light years away toward the constellation of Aquarius, and spans about
   3 light-years.

                     Tomorrow's picture: a rounder moon
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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