                        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.

                              2025 September 10
    A starfield surrounds a large red nebula. The nebula has many flowing
        waves and folds. Please see the explanation for more detailed
                                information.

                          The Great Lacerta Nebula
           Image Credit & Copyright: Ian Moehring & Kevin Roylance

   Explanation: It is one of the largest nebulas on the sky -- why isn't
   it better known? Roughly the same angular size as the Andromeda Galaxy,
   the Great Lacerta Nebula can be found toward the constellation of the
   Lizard (Lacerta). The emission nebula is difficult to see with
   wide-field binoculars because it is so faint, but also usually
   difficult to see with a large telescope because it is so great in angle
   -- spanning about three degrees. The depth, breadth, waves, and beauty
   of the nebula -- cataloged as Sharpless 126 (Sh2-126) -- can best be
   seen and appreciated with a long duration camera exposure. The featured
   image is one such combined exposure -- in this case taken over three
   nights in August through dark skies in Moses Lake, Washington, USA. The
   hydrogen gas in the Great Lacerta Nebula glows red because it is
   excited by light from the bright star 10 Lacertae, one of the bright
   blue stars just to the left of the red-glowing nebula's center. Most of
   the stars and nebula are about 1,200 light years distant.

                Jigsaw Universe: Astronomy Puzzle of the Day
                       Tomorrow's picture: shadow play
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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