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.

                              2021 September 7
     [2]The picture shows the colliding galaxies of NGC 520 as imaged by
    NASA and ESA's Hubble Space Telescope. Please see the explanation for
                         more detailed information.

                   NGC 520: Colliding Galaxies from Hubble
       Image Credit: [3]NASA, [4]ESA, Hubble; Processing & Copyright:
              [5]William Ostling ([6]The Astronomy Enthusiast)

   Explanation: Is this one galaxy or two? The jumble of stars, gas, and
   [7]dust that is [8]NGC 520 is now thought to incorporate the remains of
   two separate disk galaxies. A defining component of [9]NGC 520 -- as
   seen in great detail in the [10]featured image from the [11]Hubble
   Space Telescope -- is its [12]band of intricately interlaced dust
   running vertically down the spine of the [13]colliding galaxies. A
   similar looking collision might be expected in a few billion years when
   our disk [14]Milky Way Galaxy to [15]collides with our large-disk
   galactic neighbor [16]Andromeda (M31). The collision that defines
   [17]NGC 520 started about 300 million years ago. Also known as Arp 157,
   NGC 520 lies about 100 million [18]light years distant, spans about 100
   thousand [19]light years, and can be seen with a small telescope toward
   the [20]constellation of the Fish ([21]Pisces). Although the speeds of
   stars in [22]NGC 520 are fast, the distances are [23]so vast that the
   [24]battling pair will surely not change its shape noticeably during
   our lifetimes.

                       Tomorrow's picture: open space
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    Authors & editors: [36]Robert Nemiroff ([37]MTU) & [38]Jerry Bonnell
                                 ([39]UMCP)
          NASA Official: Phillip Newman [40]Specific rights apply.
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                A service of: [42]ASD at [43]NASA / [44]GSFC
                           & [45]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2109/NGC520_HubbleOstling_1493.jpg
   3. https://www.nasa.gov/
   4. https://esahubble.org/
   5. https://www.instagram.com/the_astronomy_enthusiast/
   6. https://theastroenthusiast.com/
   7. https://apod.nasa.gov/apod/ap030706.html
   8. https://en.wikipedia.org/wiki/NGC_520
   9. https://esahubble.org/images/heic0810aq/
  10. https://www.flickr.com/photos/192935202@N08/51398314609/
  11. https://www.nasa.gov/content/goddard/hubble-history-timeline
  12. https://apod.nasa.gov/apod/ap111129.html
  13. https://apod.nasa.gov/apod/ap130514.html
  14. https://imagine.gsfc.nasa.gov/science/objects/milkyway1.html
  15. https://apod.nasa.gov/apod/ap120604.html
  16. https://en.wikipedia.org/wiki/Andromeda_Galaxy
  17. http://www.cv.nrao.edu/~jhibbard/n520/n520.html
  18. https://chandra.harvard.edu/photo/cosmic_distance.html
  19. https://spaceplace.nasa.gov/light-year/en/
  20. https://www.iau.org/public/themes/constellations/
  21. https://chandra.harvard.edu/photo/constellations/pisces.html
  22. https://ui.adsabs.harvard.edu/abs/2005MNRAS.359..455R/abstract
  23. https://k9inebubbles.com/wp-content/uploads/2020/11/surprised-dog-heartworm.jpg
  24. https://apod.nasa.gov/apod/ap160203.html
  25. https://apod.nasa.gov/apod/ap210906.html
  26. https://apod.nasa.gov/apod/archivepix.html
  27. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  28. https://apod.nasa.gov/apod/lib/aptree.html
  29. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  30. https://apod.nasa.gov/apod/calendar/allyears.html
  31. https://apod.nasa.gov/apod.rss
  32. https://apod.nasa.gov/apod/lib/edlinks.html
  33. https://apod.nasa.gov/apod/lib/about_apod.html
  34. http://asterisk.apod.com/discuss_apod.php?date=210907
  35. https://apod.nasa.gov/apod/ap210908.html
  36. http://www.phy.mtu.edu/faculty/Nemiroff.html
  37. http://www.phy.mtu.edu/
  38. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  39. http://www.astro.umd.edu/
  40. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  41. https://www.nasa.gov/about/highlights/HP_Privacy.html
  42. https://astrophysics.gsfc.nasa.gov/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. http://www.mtu.edu/