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 March 11
     [2]A cometary globule extends in front of a field of stars, showing
        what seems like an open mouth towards a distant galaxy in the
    background. Please see the explanation for more detailed information.

                      CG 4: The Globule and the Galaxy
               Image Credit & [3]Copyright: [4]William Vrbasso
     Text: [5]Cecilia Chirenti ([6]NASA [7]GSFC, [8]UMCP, [9]CRESST II)

   Explanation: Is this a cosmic monster ready to devour an unsuspecting
   galaxy? Thankfully, that is not the case. The red “monster” shown in
   the [10]featured image is [11]Cometary Globule [12]CG 4, 1,300
   light-years away in the [13]Constellation Puppis. CG 4 is a
   [14]molecular cloud, where [15]hydrogen becomes cold enough to form
   [16]molecules that can be brought together by gravity to [17]create
   stars. The shape of CG 4 [18]resembles that of a [19]comet, but its
   head is 1.5 [20]light-year in diameter and its tail is 8 light-years
   long; for comparison, the distance from the Earth to the sun is only
   [21]8 light-minutes. Astronomers [22]believe that the tail of a
   cometary globule could have been shaped by a nearby supernova explosion
   or by irradiation from hot, massive stars. Indeed, CG 4 and other
   nearby globules [23]point away from the [24]Vela Supernova Remnant, at
   the center of the [25]Gum Nebula. The edge-on [26]spiral galaxy, ESO
   257-19, is more than a hundred million light-years beyond CG 4, and is
   completely safe from the “[27]monster”.

                         Tomorrow's picture: Uranus
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    Authors & editors: [39]Robert Nemiroff ([40]MTU) & [41]Jerry Bonnell
                                 ([42]UMCP)
          NASA Official: Amber Straughn [43]Specific rights apply.
            [44]NASA Web Privacy, [45]Accessibility, [46]Notices;
                A service of: [47]ASD at [48]NASA / [49]GSFC,
                         [50]NASA Science Activation
                           & [51]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2603/cg4.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.stellaraustralis.com/
   5. https://science.gsfc.nasa.gov/sci/bio/cecilia.bertonimarthahadlerchirenti
   6. https://www.nasa.gov/
   7. https://www.nasa.gov/goddard/
   8. https://www.astro.umd.edu/people/cecilia-chirenti
   9. https://cresst2.umd.edu/
  10. https://www.instagram.com/p/DVM1o0MkyDe/
  11. https://apod.nasa.gov/apod/ap240716.html
  12. https://en.wikipedia.org/wiki/CG_4
  13. https://earthsky.org/constellations/puppis-the-stern-argo-navis/
  14. https://www.britannica.com/science/molecular-cloud
  15. https://www.acs.org/molecule-of-the-week/archive/h/hydrogen.html
  16. https://en.wikipedia.org/wiki/Molecule
  17. https://science.nasa.gov/universe/stars/#birth
  18. https://en.wikipedia.org/wiki/Pareidolia
  19. https://www.esa.int/ESA_Multimedia/Images/2023/11/Structure_of_a_comet
  20. https://science.nasa.gov/exoplanets/what-is-a-light-year/
  21. https://www2.hao.ucar.edu/education/about-the-sun/how-far-away-sun
  22. https://noirlab.edu/public/news/noirlab2412/
  23. https://www.eso.org/public/news/eso1503/
  24. https://apod.nasa.gov/apod/ap190110.html
  25. https://apod.nasa.gov/apod/ap221129.html
  26. https://science.nasa.gov/universe/galaxies/types/
  27. https://plus.unsplash.com/premium_photo-1720922579207-251b22182659
  28. https://apod.nasa.gov/apod/ap260310.html
  29. https://apod.nasa.gov/apod/archivepix.html
  30. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  31. https://apod.nasa.gov/apod/lib/aptree.html
  32. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  33. https://apod.nasa.gov/apod/calendar/allyears.html
  34. https://apod.com/feed.rss
  35. https://apod.nasa.gov/apod/lib/edlinks.html
  36. https://apod.nasa.gov/apod/lib/about_apod.html
  37. https://asterisk.apod.com/discuss_apod.php?date=260311
  38. https://apod.nasa.gov/apod/ap260312.html
  39. http://www.phy.mtu.edu/faculty/Nemiroff.html
  40. http://www.phy.mtu.edu/
  41. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  42. http://www.astro.umd.edu/
  43. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  44. https://www.nasa.gov/about/highlights/HP_Privacy.html
  45. https://www.nasa.gov/general/accessibility/
  46. https://www.nasa.gov/privacy/
  47. https://astrophysics.gsfc.nasa.gov/
  48. https://www.nasa.gov/
  49. https://www.nasa.gov/centers/goddard/
  50. https://science.nasa.gov/learners
  51. http://www.mtu.edu/