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 December 18
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                              Stephan's Quintet
          Image Credit: [3]NASA, [4]ESA, [5]Hubble Legacy Archive;
                  Processing & Copyright: [6]Bernard Miller

   Explanation: The first identified compact galaxy group, [7]Stephan's
   Quintet is featured in [8]this eye-catching image constructed with data
   drawn from the extensive [9]Hubble Legacy Archive. About 300 million
   light-years away, only four of these five galaxies are actually locked
   in a cosmic dance of repeated close encounters. The odd man out is easy
   to spot, though. The interacting galaxies, [10]NGC 7319, 7318A, 7318B,
   and 7317 have an overall yellowish cast. They also tend to have
   distorted [11]loops and tails, grown under the influence of disruptive
   [12]gravitational tides. But the predominantly bluish galaxy, NGC 7320,
   is closer, just 40 million light-years distant, and isn't part of the
   interacting group. Stephan's Quintet lies within the boundaries of the
   high flying [13]constellation Pegasus. At the estimated distance of the
   quartet of interacting galaxies, this field of view spans about 500,000
   light-years. But moving just beyond this field, up and to the right,
   astronomers can identify another galaxy, [14]NGC 7320C, that is also
   300 million light-years distant. Including it would bring the
   [15]interacting quartet back up to quintet status.

                      Tomorrow's picture: five in a row
     __________________________________________________________________

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    Authors & editors: [27]Robert Nemiroff ([28]MTU) & [29]Jerry Bonnell
                                 ([30]UMCP)
          NASA Official: Phillip Newman [31]Specific rights apply.
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                A service of: [33]ASD at [34]NASA / [35]GSFC
                           & [36]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2112/HUBBLE_NGC7318_PS2_CROP_INSIGHT3072.jpg
   3. https://www.nasa.gov/
   4. https://www.esa.int/
   5. https://hla.stsci.edu/
   6. http://azstarman.net/CDK/index.html
   7. http://arxiv.org/abs/astro-ph/9802328
   8. http://azstarman.net/CDK/HUBBLE_NGC7318.htm
   9. http://hla.stsci.edu/
  10. https://hubblesite.org/contents/media/images/2009/25/2606-Image.html?news=true
  11. https://apod.nasa.gov/apod/ap090426.html
  12. https://apod.nasa.gov/apod/ap081115.html
  13. http://www.hawastsoc.org/deepsky/peg/index.html
  14. https://en.wikipedia.org/wiki/NGC_7320c#/media/File:StephansQuintettIlustrated2.gif
  15. http://chandra.harvard.edu/photo/2003/stephan/index.html
  16. https://apod.nasa.gov/apod/ap211217.html
  17. https://apod.nasa.gov/apod/archivepix.html
  18. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  19. https://apod.nasa.gov/apod/lib/aptree.html
  20. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  21. https://apod.nasa.gov/apod/calendar/allyears.html
  22. https://apod.nasa.gov/apod.rss
  23. https://apod.nasa.gov/apod/lib/edlinks.html
  24. https://apod.nasa.gov/apod/lib/about_apod.html
  25. http://asterisk.apod.com/discuss_apod.php?date=211218
  26. https://apod.nasa.gov/apod/ap211219.html
  27. http://www.phy.mtu.edu/faculty/Nemiroff.html
  28. http://www.phy.mtu.edu/
  29. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  30. http://www.astro.umd.edu/
  31. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  32. https://www.nasa.gov/about/highlights/HP_Privacy.html
  33. https://astrophysics.gsfc.nasa.gov/
  34. https://www.nasa.gov/
  35. https://www.nasa.gov/centers/goddard/
  36. http://www.mtu.edu/