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                        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 25

         IFRAME: [2]https://www.youtube.com/embed/l36UkYtq6m0?rel=0

                 Visualization: A Black Hole Accretion Disk
       Visualization Credit: [3]NASA's [4]Goddard Space Flight Center,
                            [5]Jeremy Schnittman

   Explanation: What would it look like to circle a black hole? If the
   [6]black hole was surrounded by a [7]swirling disk of glowing and
   accreting gas, then the great gravity of the black hole would
   [8]deflect light emitted by the disk to make it look very unusual. The
   [9]featured animated video gives a visualization. The video starts with
   you, the observer, looking toward the [10]black hole from just above
   the plane of the accretion disk. Surrounding the central [11]black hole
   is a thin circular image of the orbiting disk that marks the position
   of the [12]photon sphere -- inside of which lies the black hole's
   [13]event horizon. Toward the left, parts of the large main image of
   the disk [14]appear brighter as they move toward you. As [15]the video
   continues, you loop over the [16]black hole, soon looking down from the
   top, then passing through the disk plane on the far side, then
   returning to your [17]original vantage point. The accretion disk does
   some interesting [18]image inversions -- but never appears flat.
   Visualizations such as this are particularly relevant today as
   [19]black holes are being imaged in unprecedented detail by the
   [20]Event Horizon Telescope.

                     Tomorrow's picture: swan and galaxy
     __________________________________________________________________

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     __________________________________________________________________

    Authors & editors: [32]Robert Nemiroff ([33]MTU) & [34]Jerry Bonnell
                                 ([35]UMCP)
          NASA Official: Phillip Newman [36]Specific rights apply.
              [37]NASA Web Privacy Policy and Important Notices
                A service of: [38]ASD at [39]NASA / [40]GSFC
                           & [41]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://www.youtube.com/embed/l36UkYtq6m0?rel=0
   3. https://www.nasa.gov/
   4. https://science.gsfc.nasa.gov/sci/
   5. https://science.gsfc.nasa.gov/sed/bio/jeremy.d.schnittman
   6. https://science.nasa.gov/astrophysics/focus-areas/black-holes
   7. https://apod.nasa.gov/apod/ap190820.html
   8. https://www.phy.mtu.edu/bht/rjn_bht.html
   9. https://svs.gsfc.nasa.gov/13326
  10. https://apod.nasa.gov/apod/ap200324.html
  11. https://jila.colorado.edu/hamilton/black-holes/journey-schwarzschild-black-hole
  12. https://en.wikipedia.org/wiki/Photon_sphere
  13. https://en.wikipedia.org/wiki/Event_horizon
  14. https://en.wikipedia.org/wiki/Aberration_(astronomy)
  15. https://www.youtube.com/watch?v=l36UkYtq6m0
  16. https://ui.adsabs.harvard.edu/abs/1993AmJPh..61..619N/abstract
  17. https://apod.nasa.gov/apod/image/2008/BhAccretionDisk_NasaSchnittman_3851_annotated.jpg
  18. https://apod.nasa.gov/apod/ap141026.html
  19. https://apod.nasa.gov/apod/ap190411.html
  20. https://eventhorizontelescope.org/
  21. https://apod.nasa.gov/apod/ap200824.html
  22. https://apod.nasa.gov/apod/archivepix.html
  23. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  24. https://apod.nasa.gov/apod/lib/aptree.html
  25. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  26. https://apod.nasa.gov/apod/calendar/allyears.html
  27. https://apod.nasa.gov/apod.rss
  28. https://apod.nasa.gov/apod/lib/edlinks.html
  29. https://apod.nasa.gov/apod/lib/about_apod.html
  30. http://asterisk.apod.com/discuss_apod.php?date=200825
  31. https://apod.nasa.gov/apod/ap200826.html
  32. http://www.phy.mtu.edu/faculty/Nemiroff.html
  33. http://www.phy.mtu.edu/
  34. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  35. http://www.astro.umd.edu/
  36. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  37. https://www.nasa.gov/about/highlights/HP_Privacy.html
  38. https://astrophysics.gsfc.nasa.gov/
  39. https://www.nasa.gov/
  40. https://www.nasa.gov/centers/goddard/
  41. http://www.mtu.edu/