Astronomy Picture of the Day

   [1]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
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                         Ou4: The Giant Squid Nebula
              Image Credit & [3]Copyright: [4]Massimo Di Fusco

   Explanation: [5]Difficult to capture, this mysterious, squid-shaped
   interstellar cloud spans nearly three full moons in planet Earth's sky.
   [6]Discovered in 2011 by French astro-imager [7]Nicolas Outters, the
   Squid Nebula's [8]bipolar shape is distinguished here by the telltale
   blue [9]emission from doubly ionized oxygen atoms. Though apparently
   [10]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 [11]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 [12]triple system of hot, massive stars, cataloged
   as [13]HR8119, seen near the center of the nebula. If so, this truly
   giant squid nebula would physically be over 50 [14]light-years across.

                   Tomorrow's picture: north pole of Mars
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    Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell
                                 ([29]UMCP)
          NASA Official: Amber Straughn [30]Specific rights apply.
            [31]NASA Web Privacy, [32]Accessibility, [33]Notices;
                A service of: [34]ASD at [35]NASA / [36]GSFC,
                         [37]NASA Science Activation
                           & [38]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2507/Ou4_difusco.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://app.astrobin.com/u/massimo.difusco#gallery
   5. https://app.astrobin.com/i/hmtykv
   6. https://ui.adsabs.harvard.edu/abs/2012RMxAA..48..223A/abstract
   7. http://outters.fr/wp/?page_id=50
   8. https://apod.nasa.gov/apod/ap230416.html
   9. https://en.wikipedia.org/wiki/Nebulium
  10. https://apod.nasa.gov/apod/ap230817.html
  11. https://ui.adsabs.harvard.edu/abs/2014A&A...570A.105C/abstract
  12. http://www.atlasoftheuniverse.com/orbits.html
  13. https://in-the-sky.org/data/object.php?id=TYC3965-880-1#google_vignette
  14. https://science.nasa.gov/exoplanets/what-is-a-light-year/
  15. https://apod.nasa.gov/apod/ap250704.html
  16. https://apod.nasa.gov/apod/archivepix.html
  17. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  18. https://apod.nasa.gov/apod/lib/aptree.html
  19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  20. https://apod.nasa.gov/apod/calendar/allyears.html
  21. https://apod.com/feed.rss
  22. https://apod.nasa.gov/apod/lib/edlinks.html
  23. https://apod.nasa.gov/apod/lib/about_apod.html
  24. https://asterisk.apod.com/discuss_apod.php?date=250705
  25. https://apod.nasa.gov/apod/ap250706.html
  26. http://www.phy.mtu.edu/faculty/Nemiroff.html
  27. http://www.phy.mtu.edu/
  28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  29. http://www.astro.umd.edu/
  30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  31. https://www.nasa.gov/about/highlights/HP_Privacy.html
  32. https://www.nasa.gov/general/accessibility/
  33. https://www.nasa.gov/privacy/
  34. https://astrophysics.gsfc.nasa.gov/
  35. https://www.nasa.gov/
  36. https://www.nasa.gov/centers/goddard/
  37. https://science.nasa.gov/learners
  38. http://www.mtu.edu/