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 March 18
   [2]A dark brown cloud that appears similar to a shark is seen against a
    background filled with stars and less prominent blue-shaded nebulas.
          Please see the explanation for more detailed information.

                         LDN 1235: The Shark Nebula
                 Image Credit & Copyright: [3]Timothy Martin

   Explanation: There is no sea on Earth large enough to contain the Shark
   nebula. This [4]predator apparition poses us no danger as it is
   composed only of interstellar gas and [5]dust. Dark dust like that
   [6]featured here is somewhat like cigarette smoke and [7]created in the
   cool atmospheres of giant [8]stars. After expelling gas and
   [9]gravitationally recondensing, massive stars may [10]carve intricate
   structures into their birth cloud using their high energy light and
   fast [11]stellar winds as sculpting tools. The heat they generate
   evaporates the murky [12]molecular cloud as well as causing ambient
   hydrogen gas to disperse and glow red. During disintegration, we
   [13]humans can enjoy [14]imagining these [15]great clouds as [16]common
   icons, like we do for [17]water clouds on Earth. Including [18]smaller
   dust nebulae such as Van den Bergh 149 & 150, the [19]Shark nebula,
   sometimes cataloged as LDN 1235, spans about 15 light years and lies
   about 650 [20]light years away toward the constellation of the King of
   Aethiopia ([21]Cepheus).

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    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Amber Straughn [38]Specific rights apply.
            [39]NASA Web Privacy, [40]Accessibility, [41]Notices;
                A service of: [42]ASD at [43]NASA / [44]GSFC,
                         [45]NASA Science Activation
                           & [46]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2503/Shark_Martin_5441.jpg
   3. https://www.astrobin.com/users/AccidentalAstronomers/
   4. https://oceantoday.noaa.gov/endoceansharks/
   5. http://apod.nasa.gov/apod/ap030706.html
   6. https://www.astrobin.com/6ekkcw/
   7. https://en.wikipedia.org/wiki/Cosmic_dust#Dust_grain_formation
   8. https://science.nasa.gov/universe/stars/
   9. https://www.youtube.com/watch?v=YbdwTwB8jtc
  10. https://apod.nasa.gov/apod/ap221020.html
  11. https://apod.nasa.gov/apod/ap000318.html
  12. https://apod.nasa.gov/apod/ap230129.html
  13. https://apod.nasa.gov/apod/ap190818.html
  14. https://apod.nasa.gov/apod/ap120124.html
  15. https://apod.nasa.gov/apod/ap141008.html
  16. https://en.wikipedia.org/wiki/Pareidolia
  17. https://cloudappreciationsociety.org/
  18. https://apod.nasa.gov/apod/image/1509/shark_toet_1000_anno.jpg
  19. https://www.galactic-hunter.com/post/the-shark-nebula
  20. https://spaceplace.nasa.gov/light-year/
  21. https://en.wikipedia.org/wiki/Cepheus_(constellation)
  22. https://apod.nasa.gov/apod/random_apod.html
  23. https://apod.nasa.gov/apod/ap250317.html
  24. https://apod.nasa.gov/apod/archivepix.html
  25. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  26. https://apod.nasa.gov/apod/lib/aptree.html
  27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  28. https://apod.nasa.gov/apod/calendar/allyears.html
  29. https://apod.com/feed.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. https://asterisk.apod.com/discuss_apod.php?date=250318
  33. https://apod.nasa.gov/apod/ap250319.html
  34. http://www.phy.mtu.edu/faculty/Nemiroff.html
  35. http://www.phy.mtu.edu/
  36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  37. http://www.astro.umd.edu/
  38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  39. https://www.nasa.gov/about/highlights/HP_Privacy.html
  40. https://www.nasa.gov/general/accessibility/
  41. https://www.nasa.gov/privacy/
  42. https://astrophysics.gsfc.nasa.gov/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. https://science.nasa.gov/learners
  46. http://www.mtu.edu/