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.

                               2020 August 27
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                          Shell Galaxies in Pisces
                 Image Credit & [3]Copyright: [4]Martin Pugh

   Explanation: [5]This intergalactic skyscape features a peculiar system
   of galaxies [6]cataloged as Arp 227 some 100 million light-years
   distant. Swimming within the boundaries of the [7]constellation Pisces,
   Arp 227 consists of the two galaxies prominent right of center, the
   curious shell galaxy NGC 474 and its blue, spiral-armed neighbor NGC
   470. The faint, wide arcs or [8]shells of NGC 474 could have been
   formed by a gravitational encounter with neighbor NGC 470. Alternately
   the shells could be [9]caused by a merger with a smaller galaxy
   producing an effect analogous to ripples across the surface of a pond.
   The large galaxy on the top lefthand side of the deep image, NGC 467,
   appears to be surrounded by faint shells too, evidence of another
   [10]interacting galaxy system. Intriguing background galaxies are
   scattered around the field that also includes spiky foreground stars.
   Of course, those stars lie well within our own [11]Milky Way Galaxy.
   The field of view spans 25 arc minutes or about 1/2 degree [12]on the
   sky.

                      Tomorrow's picture: in the valley
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    Authors & editors: [24]Robert Nemiroff ([25]MTU) & [26]Jerry Bonnell
                                 ([27]UMCP)
          NASA Official: Phillip Newman [28]Specific rights apply.
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                A service of: [30]ASD at [31]NASA / [32]GSFC
                           & [33]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2008/ngc474MP.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.martinpughastrophotography.space/about
   5. https://www.martinpughastrophotography.space/ngc-474
   6. http://nedwww.ipac.caltech.edu/level5/Arp/frames.html
   7. http://www.pa.msu.edu/people/horvatin/Astronomy_Facts/constellation_pages/pisces.htm
   8. http://adsabs.harvard.edu/abs/1999IAUS..186..191T
   9. https://apod.nasa.gov/apod/ap021111.html
  10. https://svs.gsfc.nasa.gov/30955
  11. https://apod.nasa.gov/apod/ap080104.html
  12. http://chandra.harvard.edu/photo/scale.html
  13. https://apod.nasa.gov/apod/ap200826.html
  14. https://apod.nasa.gov/apod/archivepix.html
  15. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  16. https://apod.nasa.gov/apod/lib/aptree.html
  17. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  18. https://apod.nasa.gov/apod/calendar/allyears.html
  19. https://apod.nasa.gov/apod.rss
  20. https://apod.nasa.gov/apod/lib/edlinks.html
  21. https://apod.nasa.gov/apod/lib/about_apod.html
  22. http://asterisk.apod.com/discuss_apod.php?date=200827
  23. https://apod.nasa.gov/apod/ap200828.html
  24. http://www.phy.mtu.edu/faculty/Nemiroff.html
  25. http://www.phy.mtu.edu/
  26. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  27. http://www.astro.umd.edu/
  28. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  29. https://www.nasa.gov/about/highlights/HP_Privacy.html
  30. https://astrophysics.gsfc.nasa.gov/
  31. https://www.nasa.gov/
  32. https://www.nasa.gov/centers/goddard/
  33. http://www.mtu.edu/