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.

                                 2026 May 20
   [2]A dark and whispy cloud blocks the background light from surrounding
      gas and stars. It resembles the head, snout, and jaws of a wolf.

                            The Dark Wolf Nebula
                Image Credit & Copyright: [3]William Vrbasso
   Text: [4]Keighley Rockcliffe ([5]NASA [6]GSFC, [7]UMBC CSST, [8]CRESST
                                     II)

   Explanation: A dark wolf lies in gum. No, this isn’t a riddle!
   [9]Today's image features [10]the Dark Wolf Nebula
   ([11]Sandqvist–Lindroos 17), a spooky dust cloud embedded within the
   [12]Gum 55 ([13]RCW 113) Nebula in [14]the Scorpius constellation.
   While [15]dust is a pest to us, it serves a vital role in creating the
   necessary conditions for [16]stars to be born. The Dark Wolf absorbs
   the intense [17]ultraviolet and [18]visible light emitted by young
   stars in Gum 55 and re-emits it at longer, mainly [19]infrared,
   wavelengths. This prevents the higher energy light from heating up the
   gas in the region. When a region of gas is cool enough, gravity takes
   over and causes the gas to collapse into a star. Not only does [20]dust
   act as an interstellar thermostat, but it is also [21]the meet-cute for
   single hydrogen atoms forming molecular hydrogen, the building block
   for stars. The seemingly sinister Dark Wolf is actually a harbinger of
   cosmic life.

                          Tomorrow's picture: write
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    Authors & editors: [33]Robert Nemiroff ([34]MTU) & [35]Jerry Bonnell
                                 ([36]UMCP)
          NASA Official: Amber Straughn [37]Specific rights apply.
            [38]NASA Web Privacy, [39]Accessibility, [40]Notices;
                A service of: [41]ASD at [42]NASA / [43]GSFC,
                         [44]NASA Science Activation
                           & [45]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2605/dark_wolf.jpg
   3. https://www.stellaraustralis.com/
   4. https://kerockcliffe.com/
   5. https://science.gsfc.nasa.gov/sci/bio/keighley.e.rockcliffe
   6. https://www.nasa.gov/goddard/
   7. https://csst.umbc.edu/directory/
   8. https://cresst2.umd.edu/
   9. https://www.instagram.com/p/DKYkOj9PUVg/
  10. https://www.eso.org/public/news/eso2416/
  11. https://ui.adsabs.harvard.edu/scan/manifest/1976A&A....53..179S
  12. https://articles.adsabs.harvard.edu/pdf/1955MmRAS..67..155G
  13. https://articles.adsabs.harvard.edu/pdf/1960MNRAS.121..103R
  14. https://apod.nasa.gov/apod/ap210616.html
  15. https://science.nasa.gov/universe/dust-in-the-stellar-wind-a-cosmological-primer/
  16. https://science.nasa.gov/universe/stars/
  17. https://science.nasa.gov/ems/10_ultravioletwaves/
  18. https://science.nasa.gov/ems/09_visiblelight/
  19. https://science.nasa.gov/ems/07_infraredwaves/
  20. https://astronomy.swin.edu.au/cosmos/d/Dust+Grain
  21. https://en.wikipedia.org/wiki/Meet_cute
  22. https://apod.nasa.gov/apod/ap260519.html
  23. https://apod.nasa.gov/apod/archivepix.html
  24. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  25. https://apod.nasa.gov/apod/lib/aptree.html
  26. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  27. https://apod.nasa.gov/apod/calendar/allyears.html
  28. https://apod.com/feed.rss
  29. https://apod.nasa.gov/apod/lib/edlinks.html
  30. https://apod.nasa.gov/apod/lib/about_apod.html
  31. https://asterisk.apod.com/discuss_apod.php?date=260520
  32. https://apod.nasa.gov/apod/ap260521.html
  33. http://www.phy.mtu.edu/faculty/Nemiroff.html
  34. http://www.phy.mtu.edu/
  35. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  36. http://www.astro.umd.edu/
  37. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  38. https://www.nasa.gov/about/highlights/HP_Privacy.html
  39. https://www.nasa.gov/general/accessibility/
  40. https://www.nasa.gov/privacy/
  41. https://astrophysics.gsfc.nasa.gov/
  42. https://www.nasa.gov/
  43. https://www.nasa.gov/centers/goddard/
  44. https://science.nasa.gov/learners
  45. http://www.mtu.edu/