                        Astronomy Picture of the Day

    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
    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: Claire Lamman/DESI collaboration
             Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)

   Explanation: This is a map of the universe. The Dark Energy
   Spectroscopic Instrument (DESI) at Kitt Peak National Observatory,
   Arizona, has finished its five-year survey. It observed more than 47
   million galaxies and quasars and created a 3D map centered on the
   Earth. Today's featured image shows a thin slice of these data: the
   black gaps indicate where our Galaxy obscures distant objects. The
   feathery web in the inset shows the large scale structure of the
   universe. Light of the most distant galaxies shown here travelled for
   11 billion years to reach the Earth. Galaxies cluster throughout cosmic
   history under the competing influences of gravity and dark energy,
   responsible for the accelerated expansion of the universe. Analysis of
   early DESI results hinted at the possibility that dark energy,
   described as a cosmological constant by 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 mystery
   of cosmology.

               Tomorrow's picture: young moon and sister stars
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
                  NASA Web Privacy, Accessibility, Notices;
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

