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 April 17
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                      The Windmill and the Star Trails
              Image Credit & [3]Copyright: [4]Antonio Gonzalez

   Explanation: Stars can't turn these old wooden arms, but it does look
   like they might in this scene [5]from a rotating planet. The
   well-composed night skyscape was recorded from Garafia, a municipality
   on the island of La Palma, Canary Islands, [6]planet Earth. The center
   of the once working windmill, retired since 1953, is lined-up with the
   [7]north celestial pole, the planet's rotation axis projected on to the
   northern sky. From a camera fixed to a tripod, the star trails are a
   reflection of the planet's rotation traced in a digital composite of 39
   sequential exposures each 25 seconds long. Brought out by highlighting
   the final exposure in the sequence, the stars themselves appear at the
   ends of their short concentric arcs. A faint band of winter's Milky Way
   and even a diffuse glow from our neighboring Andromeda Galaxy also
   shine [8]in the night.

                      Tomorrow's picture: light-weekend
     __________________________________________________________________

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    Authors & editors: [20]Robert Nemiroff ([21]MTU) & [22]Jerry Bonnell
                                 ([23]UMCP)
          NASA Official: Phillip Newman [24]Specific rights apply.
              [25]NASA Web Privacy Policy and Important Notices
                A service of: [26]ASD at [27]NASA / [28]GSFC
                           & [29]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2004/WindmillStarTrails.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. mailto:%20astrojagh%20[at]%20gmail%20[dot]%20com
   5. https://www.nasa.gov/content/earth-day-2020
   6. https://earthobservatory.nasa.gov/images/81421/trailing-the-canaries
   7. https://apod.nasa.gov/apod/ap131023.html
   8. https://apod.nasa.gov/apod/ap150110.html
   9. https://apod.nasa.gov/apod/ap200416.html
  10. https://apod.nasa.gov/apod/archivepix.html
  11. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  12. https://apod.nasa.gov/apod/lib/aptree.html
  13. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  14. https://apod.nasa.gov/apod/calendar/allyears.html
  15. https://apod.nasa.gov/apod.rss
  16. https://apod.nasa.gov/apod/lib/edlinks.html
  17. https://apod.nasa.gov/apod/lib/about_apod.html
  18. http://asterisk.apod.com/discuss_apod.php?date=200417
  19. https://apod.nasa.gov/apod/ap200418.html
  20. http://www.phy.mtu.edu/faculty/Nemiroff.html
  21. http://www.phy.mtu.edu/
  22. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  23. http://www.astro.umd.edu/
  24. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  25. https://www.nasa.gov/about/highlights/HP_Privacy.html
  26. https://astrophysics.gsfc.nasa.gov/
  27. https://www.nasa.gov/
  28. https://www.nasa.gov/centers/goddard/
  29. http://www.mtu.edu/