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 March 26

                              The Medusa Nebula
                   Image Credit & Copyright: Josep Drudis

   Explanation: Braided and serpentine filaments of glowing gas suggest
   this nebula's popular name, The Medusa Nebula. Also known as Abell 21,
   this Medusa is an old planetary nebula some 1,500 light-years away in
   the constellation Gemini. Like its mythological namesake, the nebula is
   associated with a dramatic transformation. The planetary nebula phase
   represents a final stage in the evolution of low mass stars like the
   sun as they transform themselves from red giants to hot white dwarf
   stars and in the process shrug off their outer layers. Ultraviolet
   radiation from the hot star powers the nebular glow. The Medusa's
   transforming star is the faint one near the center of the overall
   bright crescent shape. In this deep telescopic view, fainter filaments
   clearly extend above and right of the bright crescent region. The
   Medusa Nebula is estimated to be over 4 light-years across.

                      Tomorrow's picture: light weekend
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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