                        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.

                                2024 June 17
     A starfield has a red nebula covering much of the frame but in the
     center, extending nearly vertically, is a blue nebula that appears
     shaped, to some, like a squid. Please see the explanation for more
                            detailed information.

                         Ou4: The Giant Squid Nebula
                    Image Credit & Copyright: Alex Linde

   Explanation: Squids on Earth aren't this big. This mysterious
   squid-like cosmic cloud spans nearly three full moons on 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: thunder jets
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                             & Michigan Tech. U.

