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 June 1
       [2]The picture shows Saturn's Moon Mimas featuring a very large
        circular crater. Please see the explanation for more detailed
                                information.

                             Starlink over Orion
                      Image Credit: [3]Amir H. Abolfath

   Explanation: What are those streaks across Orion? Most are reflections
   of sunlight from numerous Earth-orbiting Starlink satellites. Appearing
   by eye as a series of [4]successive points floating across a twilight
   sky, the increasing number of [5]SpaceX Starlink communication
   satellites are [6]causing concern among many astronomers. On the
   positive side, [7]Starlink and [8]similar constellations make the
   post-sunset sky more dynamic, satellite-based global communications
   faster, and help provide [9]digital services to currently underserved
   rural areas. On the [10]negative side, though, these [11]low
   Earth-orbit satellites make [12]some deep astronomical imaging programs
   more difficult, in particular observing programs that need images taken
   just after sunset and just before dawn. Planned future satellite arrays
   that function in higher orbits may [13]impact investigations of the
   deep universe planned for [14]large ground-based telescopes at any time
   during the night. The [15]featured picture, taken in 2019 December, is
   a digital combination of over 65 3-minutes exposures, with some images
   taken to highlight the background [16]Orion Nebula, while others to
   feature the passing satellites.

          SatCon2 Wokshop 12-16 July 2021: [17]Mitigating Satellite
                               Constellations
                       Tomorrow's picture: open space
     __________________________________________________________________

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    Authors & editors: [29]Robert Nemiroff ([30]MTU) & [31]Jerry Bonnell
                                 ([32]UMCP)
          NASA Official: Phillip Newman [33]Specific rights apply.
              [34]NASA Web Privacy Policy and Important Notices
                A service of: [35]ASD at [36]NASA / [37]GSFC
                           & [38]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2106/StarlinkOrion_Abolfath_2138.jpg
   3. http://amir.torgheh.ir/
   4. https://youtu.be/ihVuz8uM1qU?t=13
   5. https://www.spacex.com/updates/starlink-mission-05-09-2021/index.html
   6. https://archiecat.com/wp-content/uploads/2020/01/scared-cat.jpg
   7. https://en.wikipedia.org/wiki/Starlink
   8. https://en.wikipedia.org/wiki/Satellite_internet_constellation
   9. https://skopemag.com/2020/05/20/how-do-cell-phones-use-satellites
  10. https://apod.nasa.gov/apod/ap191014.html
  11. https://www.nasa.gov/leo-economy/faqs
  12. https://noirlab.edu/public/news/noirlab2022/
  13. https://www.scientificamerican.com/article/spacexs-dark-satellites-are-still-too-bright-for-astronomers/
  14. https://en.wikipedia.org/wiki/List_of_largest_optical_reflecting_telescopes
  15. https://noirlab.edu/public/images/ann21021b/
  16. https://apod.nasa.gov/apod/ap210509.html
  17. https://noirlab.edu/public/announcements/ann21021/
  18. https://apod.nasa.gov/apod/ap210531.html
  19. https://apod.nasa.gov/apod/archivepix.html
  20. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  21. https://apod.nasa.gov/apod/lib/aptree.html
  22. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  23. https://apod.nasa.gov/apod/calendar/allyears.html
  24. https://apod.nasa.gov/apod.rss
  25. https://apod.nasa.gov/apod/lib/edlinks.html
  26. https://apod.nasa.gov/apod/lib/about_apod.html
  27. http://asterisk.apod.com/discuss_apod.php?date=210601
  28. https://apod.nasa.gov/apod/ap210602.html
  29. http://www.phy.mtu.edu/faculty/Nemiroff.html
  30. http://www.phy.mtu.edu/
  31. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  32. http://www.astro.umd.edu/
  33. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  34. https://www.nasa.gov/about/highlights/HP_Privacy.html
  35. https://astrophysics.gsfc.nasa.gov/
  36. https://www.nasa.gov/
  37. https://www.nasa.gov/centers/goddard/
  38. http://www.mtu.edu/