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.

                                2026 March 20
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                     Spring Equinox at Teide Observatory
    Image Credit & [3]Copyright: [4]Juan Carlos Casado ([5]Starry Earth,
                                  [6]TWAN)

   Explanation: [7]The defining astronomical moment of the equinox today
   is at 14:46 UTC (March 20). That's when the Sun [8]crosses the
   celestial equator moving north in its yearly journey through planet
   Earth's sky, marking the beginning of spring for our fair planet in the
   northern hemisphere and fall in the southern hemisphere. Then, day and
   night are nearly equal [9]around the globe. In fact, both day and
   nighttime exposures from a spring equinox at the [10]Observatorio del
   Teide in Tenerife, Canary Islands, Spain, are used in this composited
   skyscape. Over 1,000 images were taken with a fisheye lens and merged
   in the ambitious equinox project. The apparent motion of the Sun
   setting along the celestial equator on the equinox date follows the
   bright linear, diagonal track from the sequence of daytime exposures
   taken over 6 hours. After sunset, nighttime exposures recorded
   startrails, with the [11]celestial equator as a linear track and
   concentric arcs circling the north celestial pole near Polaris at upper
   right and the south celestial pole beyond the lower left edge (and
   below the Teide horizon). The foreground includes the distant [12]Teide
   volcano peak [13]and the observatory's pyramid-shaped solar laboratory
   building.

                  Tomorrow's picture: NGC 1300 and Friends
     __________________________________________________________________

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    Authors & editors: [25]Robert Nemiroff ([26]MTU) & [27]Jerry Bonnell
                                 ([28]UMCP)
          NASA Official: Amber Straughn [29]Specific rights apply.
            [30]NASA Web Privacy, [31]Accessibility, [32]Notices;
                A service of: [33]ASD at [34]NASA / [35]GSFC,
                         [36]NASA Science Activation
                           & [37]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2603/equinox-3k-jcc.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.twanight.org/casado
   5. https://www.flickr.com/photos/starryearth/albums/
   6. https://www.twanight.org/
   7. https://earthsky.org/astronomy-essentials/everything-you-need-to-know-vernal-or-spring-equinox/
   8. https://www.timeanddate.com/calendar/march-equinox.html
   9. https://svs.gsfc.nasa.gov/11353
  10. https://www.iac.es/en/observatorios-de-canarias/teide-observatory
  11. https://apod.nasa.gov/apod/ap021115.html
  12. https://apod.nasa.gov/apod/ap231203.html
  13. https://apod.nasa.gov/apod/ap121213.html
  14. https://apod.nasa.gov/apod/ap260319.html
  15. https://apod.nasa.gov/apod/archivepix.html
  16. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  17. https://apod.nasa.gov/apod/lib/aptree.html
  18. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  19. https://apod.nasa.gov/apod/calendar/allyears.html
  20. https://apod.com/feed.rss
  21. https://apod.nasa.gov/apod/lib/edlinks.html
  22. https://apod.nasa.gov/apod/lib/about_apod.html
  23. https://asterisk.apod.com/discuss_apod.php?date=260320
  24. https://apod.nasa.gov/apod/ap260321.html
  25. http://www.phy.mtu.edu/faculty/Nemiroff.html
  26. http://www.phy.mtu.edu/
  27. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  28. http://www.astro.umd.edu/
  29. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  30. https://www.nasa.gov/about/highlights/HP_Privacy.html
  31. https://www.nasa.gov/general/accessibility/
  32. https://www.nasa.gov/privacy/
  33. https://astrophysics.gsfc.nasa.gov/
  34. https://www.nasa.gov/
  35. https://www.nasa.gov/centers/goddard/
  36. https://science.nasa.gov/learners
  37. http://www.mtu.edu/