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.

                                 2025 May 21
     [2]The Sun is pictured complete with active regions, filaments, and
    prominences. Down the Sun's face is a series of silhouettes that are
   the International Space Station passing right in front. Please see the
                 explanation for more detailed information.

                 International Space Station Crosses the Sun
               Image Credit & Copyright: [3]Pau Montplet Sanz

   Explanation: Typically, the International Space Station is visible only
   at night. Slowly drifting across the night sky as it orbits the Earth,
   the [4]International Space Station (ISS) can be seen as a [5]bright
   spot about once a month from many locations. [6]The ISS is then visible
   only just after sunset or just before sunrise because it shines by
   reflected sunlight -- once the [7]ISS enters the [8]Earth's shadow, it
   will drop [9]out of sight. The only occasion when the [10]ISS is
   visible during the day is when it [11]passes right in front of the Sun.
   Then, it passes so quickly that only cameras taking short exposures can
   visually freeze the [12]ISS's silhouette onto the background [13]Sun.
   The [14]featured picture did exactly that -- it is actually a series of
   images taken a month ago from [15]Sant Feliu de Buixalleu, [16]Spain
   with perfect timing. [17]This image series was later combined with a
   separate image highlighting the texture of the active Sun which
   included several [18]Sun's prominences around the edge.

   Celestial Surprise: [19]What picture did APOD feature on your birthday?
                                 (post 1995)
                       Tomorrow's picture: pluto below
     __________________________________________________________________

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     __________________________________________________________________

    Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell
                                 ([34]UMCP)
          NASA Official: Amber Straughn [35]Specific rights apply.
            [36]NASA Web Privacy, [37]Accessibility, [38]Notices;
                A service of: [39]ASD at [40]NASA / [41]GSFC,
                         [42]NASA Science Activation
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2505/IssTransit_Sanz_2569.jpg
   3. https://www.instagram.com/astro_breda/
   4. https://www.nasa.gov/international-space-station/
   5. https://apod.nasa.gov/apod/ap200528.html
   6. https://spotthestation.nasa.gov/faq.cfm
   7. https://apod.nasa.gov/apod/ap161105.html
   8. https://apod.nasa.gov/apod/ap080820.html
   9. https://www.reddit.com/r/FindTheSniper/comments/1chffk6/find_the_cat/#lightbox
  10. https://apod.nasa.gov/apod/ap160513.html
  11. https://apod.nasa.gov/apod/ap190715.html
  12. https://apod.nasa.gov/apod/ap150912.html
  13. https://science.nasa.gov/sun/
  14. https://www.instagram.com/p/DIrW8Vuoh-f/
  15. https://en.wikipedia.org/wiki/Sant_Feliu_de_Buixalleu
  16. https://en.wikipedia.org/wiki/Spain
  17. https://apod.nasa.gov/apod/image/2505/IssTransit_Sanz.mp4
  18. https://apod.nasa.gov/apod/ap180618.html
  19. https://apod.nasa.gov/apod/calendar/allyears.html
  20. https://apod.nasa.gov/apod/ap250520.html
  21. https://apod.nasa.gov/apod/archivepix.html
  22. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  23. https://apod.nasa.gov/apod/lib/aptree.html
  24. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  25. https://apod.nasa.gov/apod/calendar/allyears.html
  26. https://apod.com/feed.rss
  27. https://apod.nasa.gov/apod/lib/edlinks.html
  28. https://apod.nasa.gov/apod/lib/about_apod.html
  29. https://asterisk.apod.com/discuss_apod.php?date=250521
  30. https://apod.nasa.gov/apod/ap250522.html
  31. http://www.phy.mtu.edu/faculty/Nemiroff.html
  32. http://www.phy.mtu.edu/
  33. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  34. http://www.astro.umd.edu/
  35. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  36. https://www.nasa.gov/about/highlights/HP_Privacy.html
  37. https://www.nasa.gov/general/accessibility/
  38. https://www.nasa.gov/privacy/
  39. https://astrophysics.gsfc.nasa.gov/
  40. https://www.nasa.gov/
  41. https://www.nasa.gov/centers/goddard/
  42. https://science.nasa.gov/learners
  43. http://www.mtu.edu/