                        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.

                               2022 October 12

                         Ou4: The Giant Squid Nebula
                    Image Credit & Copyright: Tommy Lease

   Explanation: A mysterious squid-like cosmic cloud, this nebula is very
   faint, but also very large in planet Earth's sky. In the image,
   composed with 30 hours of narrowband image data, it spans nearly three
   full moons toward the royal constellation Cepheus. Discovered in 2011
   by French astro-imager Nicolas Outters, the Squid Nebula's bipolar
   shape is distinguished here by the telltale blue-green 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, a more
   recent 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: dust shells in space
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
                NASA Web Privacy Policy and Important Notices
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

