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 April 23
   [2]The image shows a circle with bands of different colors, missing two
      opposite pizza slices, on a dark background. An inset presents a
      zoomed-in view of the center, showing a fine, feathery structure.

                    Large Scale Structure of the Universe
            Image Credit: [3]Claire Lamman/[4]DESI collaboration
     Text: [5]Cecilia Chirenti ([6]NASA [7]GSFC, [8]UMCP, [9]CRESST II)

   Explanation: This is a map of the universe. The [10]Dark Energy
   Spectroscopic Instrument (DESI) at [11]Kitt Peak National Observatory,
   [12]Arizona, has finished its [13]five-year survey. It observed more
   than 47 million galaxies and quasars and created a [14]3D map centered
   on the Earth. Today's [15]featured image shows a thin slice of these
   data: the black gaps indicate where [16]our Galaxy obscures distant
   objects. The feathery web in the inset shows the [17]large scale
   structure of the universe. Light of the most distant galaxies shown
   here travelled for [18]11 billion years to reach the Earth. Galaxies
   cluster throughout [19]cosmic history under the competing influences of
   [20]gravity and [21]dark energy, responsible for the [22]accelerated
   expansion of the universe. Analysis of [23]early DESI results hinted at
   the possibility that dark energy, described as a cosmological constant
   by [24]Albert Einstein, may not be constant after all. But we still
   have to wait for the analysis of the now complete dataset. The nature
   of dark energy is the biggest [25]mystery of cosmology.

               Tomorrow's picture: young moon and sister stars
     __________________________________________________________________

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    Authors & editors: [37]Robert Nemiroff ([38]MTU) & [39]Jerry Bonnell
                                 ([40]UMCP)
          NASA Official: Amber Straughn [41]Specific rights apply.
            [42]NASA Web Privacy, [43]Accessibility, [44]Notices;
                A service of: [45]ASD at [46]NASA / [47]GSFC,
                         [48]NASA Science Activation
                           & [49]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2604/noirlab2610c.jpg
   3. https://cmlamman.github.io/
   4. https://www.desi.lbl.gov/
   5. https://science.gsfc.nasa.gov/sci/bio/cecilia.chirenti
   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.desi.lbl.gov/
  11. https://kpno.noirlab.edu/
  12. https://en.wikipedia.org/wiki/Arizona
  13. https://noirlab.edu/public/news/noirlab2610/
  14. https://www.youtube.com/watch?v=VSTGiRLWzS4
  15. https://noirlab.edu/public/images/noirlab2610c/
  16. https://science.nasa.gov/resource/the-milky-way-galaxy/
  17. https://apod.nasa.gov/apod/ap071211.html
  18. https://starwalk.space/en/infographics/entire-universe-in-1-year
  19. https://science.nasa.gov/universe/overview/
  20. https://gracefo.jpl.nasa.gov/news/5/what-is-gravity/
  21. https://science.nasa.gov/dark-energy/
  22. https://science.nasa.gov/mission/hubble/science/science-highlights/discovering-a-runaway-universe/
  23. https://iopscience.iop.org/article/10.1088/1475-7516/2025/02/021
  24. https://www.aps.org/archives/publications/apsnews/200507/history.cfm
  25. https://images.unsplash.com/photo-1730804518415-75297e8d2a41
  26. https://apod.nasa.gov/apod/ap260422.html
  27. https://apod.nasa.gov/apod/archivepix.html
  28. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  29. https://apod.nasa.gov/apod/lib/aptree.html
  30. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  31. https://apod.nasa.gov/apod/calendar/allyears.html
  32. https://apod.com/feed.rss
  33. https://apod.nasa.gov/apod/lib/edlinks.html
  34. https://apod.nasa.gov/apod/lib/about_apod.html
  35. https://asterisk.apod.com/discuss_apod.php?date=260423
  36. https://apod.nasa.gov/apod/ap260424.html
  37. http://www.phy.mtu.edu/faculty/Nemiroff.html
  38. http://www.phy.mtu.edu/
  39. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  40. http://www.astro.umd.edu/
  41. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  42. https://www.nasa.gov/about/highlights/HP_Privacy.html
  43. https://www.nasa.gov/general/accessibility/
  44. https://www.nasa.gov/privacy/
  45. https://astrophysics.gsfc.nasa.gov/
  46. https://www.nasa.gov/
  47. https://www.nasa.gov/centers/goddard/
  48. https://science.nasa.gov/learners
  49. http://www.mtu.edu/