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 21
     [2]On a dark background, galaxies are shown as fuzzy white dots. A
     bright blue spiral expands from the center. Clicking on the picture
           will download the highest resolution version available.

                       A Collision of Galaxy Clusters
       Image Credit: X-ray: [3]NASA/[4]CXC/[5]CfA/[6]C. Watson et al.;
   Optical: [7]PanSTARRS; Image Processing: [8]NASA/[9]CXC/[10]SAO/[11]N.
                           Wolk and [12]P. Edmonds
   Text: [13]Cecilia Chirenti ([14]NASA [15]GSFC, [16]UMCP, [17]CRESST II)

   Explanation: This big beautiful [18]spiral shines in [19]X-ray light.
   It is about 20 times larger than our [20]Galaxy. It belongs to
   [21]Abell 2029, a [22]galaxy cluster one billion [23]light-years away.
   (To see only the galaxies, hover your cursor over the image, or follow
   this [24]link.) Galaxy clusters are the [25]largest structures in the
   universe that are [26]supported by gravity. Abell 2029 is formed by
   [27]thousands of galaxies, surrounded by a huge cloud of hot gas and
   the equivalent of hundreds of trillions times the mass of the Sun in
   [28]dark matter. The spiral is made of gas, mostly hydrogen and helium,
   heated to tens of millions of degrees. It was found in a [29]recent
   study that used data from NASA's [30]Chandra X-ray Observatory to show
   that Abell 2029 had a collision with a smaller cluster four billion
   years ago. The [31]collision affected the gravitational field and
   caused the intracluster gas to slosh, like wine moving in a [32]wine
   glass, shaping the spiral.

                      Tomorrow's picture: stellar winds
     __________________________________________________________________

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    Authors & editors: [44]Robert Nemiroff ([45]MTU) & [46]Jerry Bonnell
                                 ([47]UMCP)
          NASA Official: Amber Straughn [48]Specific rights apply.
            [49]NASA Web Privacy, [50]Accessibility, [51]Notices;
                A service of: [52]ASD at [53]NASA / [54]GSFC,
                         [55]NASA Science Activation
                           & [56]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2605/a2029_lg.jpg
   3. https://www.nasa.gov/
   4. https://science.nasa.gov/mission/chandra/
   5. https://www.cfa.harvard.edu/
   6. https://iopscience.iop.org/article/10.3847/1538-4357/ae2026
   7. https://panstarrs.ifa.hawaii.edu/
   8. https://www.nasa.gov/
   9. https://science.nasa.gov/mission/chandra/
  10. https://www.cfa.harvard.edu/about/about-smithsonian-astrophysical-observatory
  11. https://www.cfa.harvard.edu/people/nancy-ra-wolk
  12. https://www.cfa.harvard.edu/people/peter-edmonds
  13. https://science.gsfc.nasa.gov/sci/bio/cecilia.chirenti
  14. https://www.nasa.gov/
  15. https://www.nasa.gov/goddard/
  16. https://www.astro.umd.edu/people/cecilia-chirenti
  17. https://cresst2.umd.edu/
  18. https://chandra.si.edu/photo/2026/a2029/
  19. https://science.nasa.gov/ems/11_xrays/
  20. https://www.youtube.com/watch?v=MX3PIkbTQwQ&t=44s
  21. https://en.wikipedia.org/wiki/Abell_2029
  22. https://chandra.harvard.edu/xray_sources/galaxy_clusters.html
  23. https://en.wikipedia.org/wiki/Light-year
  24. https://apod.nasa.gov/apod/image/2605/a2029_optical.jpg
  25. https://science.nasa.gov/universe/galaxies/large-scale-structures/
  26. https://apod.nasa.gov/apod/ap190226.html
  27. https://apod.nasa.gov/apod/ap240327.html
  28. https://science.nasa.gov/dark-matter/
  29. https://iopscience.iop.org/article/10.3847/1538-4357/ae2026
  30. https://science.nasa.gov/mission/chandra/
  31. https://apod.nasa.gov/apod/ap000306.html
  32. https://images.unsplash.com/photo-1700455350393-34e80e3e0997
  33. https://apod.nasa.gov/apod/ap260520.html
  34. https://apod.nasa.gov/apod/archivepix.html
  35. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  36. https://apod.nasa.gov/apod/lib/aptree.html
  37. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  38. https://apod.nasa.gov/apod/calendar/allyears.html
  39. https://apod.com/feed.rss
  40. https://apod.nasa.gov/apod/lib/edlinks.html
  41. https://apod.nasa.gov/apod/lib/about_apod.html
  42. https://asterisk.apod.com/discuss_apod.php?date=260521
  43. https://apod.nasa.gov/apod/ap260522.html
  44. http://www.phy.mtu.edu/faculty/Nemiroff.html
  45. http://www.phy.mtu.edu/
  46. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  47. http://www.astro.umd.edu/
  48. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  49. https://www.nasa.gov/about/highlights/HP_Privacy.html
  50. https://www.nasa.gov/general/accessibility/
  51. https://www.nasa.gov/privacy/
  52. https://astrophysics.gsfc.nasa.gov/
  53. https://www.nasa.gov/
  54. https://www.nasa.gov/centers/goddard/
  55. https://science.nasa.gov/learners
  56. http://www.mtu.edu/