                        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 17
    A starfield surrounds a several large nebulas that appear mostly red
   but also white and blue. Dark dust and blue filaments also populate the
      frame. Please see the explanation for more detailed information.

                     Nebulas and Clusters in Sagittarius
     Image Credit & Copyright: J. De Winter, C. Humbert, C. Robert & V.
                      Sabet; Text: Ogetay Kayali (MTU)

   Explanation: Can you spot famous celestial objects in this image?
   18th-century astronomer Charles Messier cataloged only two of them: the
   bright Lagoon Nebula (M8) at the bottom, and the colorful Trifid Nebula
   (M20) at the upper right. The one on the left that resembles a cat's
   paw is NGC 6559, and it is much fainter than the other two. Even harder
   to spot are the thin blue filaments on the left, from supernova remnant
   (SNR G007.5-01.7). Their glow comes from small amounts of glowing
   oxygen atoms that are so faint that it took over 17 hours of exposure
   with just one blue color to bring up. Framing this scene of stellar
   birth and death are two star clusters: the open cluster M21 just above
   Trifid, and the globular cluster NGC 6544 at lower left.

                        Tomorrow's picture: NGC 6914
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                             & Michigan Tech. U.

