                        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 July 5

                         Ou4: The Giant Squid Nebula
                 Image Credit & Copyright: Massimo Di Fusco

   Explanation: Difficult to capture, this mysterious, squid-shaped
   interstellar cloud spans nearly three full moons in planet Earth's sky.
   Discovered in 2011 by French astro-imager Nicolas Outters, the Squid
   Nebula's bipolar shape is distinguished here by the telltale blue
   emission from doubly ionized oxygen atoms. Though apparently surrounded
   by the reddish hydrogen emission region Sh2-129, the true distance and
   nature of the Squid Nebula have been difficult to determine. Still, one
   investigation suggests Ou4 really does lie within Sh2-129 some 2,300
   light-years away. Consistent with that scenario, the cosmic squid would
   represent a spectacular outflow of material driven by a triple system
   of hot, massive stars, cataloged as HR8119, seen near the center of the
   nebula. If so, this truly giant squid nebula would physically be over
   50 light-years across.

                   Tomorrow's picture: north pole of Mars
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
                  NASA Web Privacy, Accessibility, Notices;
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

