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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.

                                2021 March 21
   [2]The ancient Antikythera mechanism is shown, the oldest known orrery.
                              See Explanation.

                          The Antikythera Mechanism
             Image Credit & [3]License: [4]Marsyas, [5]Wikipedia

   Explanation: No one knew that 2,000 years ago, the technology existed
   to build such a device. The [6]Antikythera mechanism, pictured, is now
   widely regarded as the [7]first [8]computer. Found at the bottom of the
   sea aboard a decaying [9]Greek ship, its complexity prompted decades of
   study, and even today some of its functions likely [10]remain unknown.
   [11]X-ray images of the device, however, have confirmed that a main
   function of its numerous clock-like [12]wheels and gears is to create a
   portable, hand-cranked, Earth-centered, [13]orrery of the sky,
   predicting future star and planet locations as well as [14]lunar and
   [15]solar eclipses. The corroded core of the [16]Antikythera
   mechanism's largest gear is featured, spanning about 13 centimeters,
   while the [17]entire mechanism was 33 centimeters high, making it
   similar in size to a large book. Recently, [18]modern computer modeling
   of missing components is allowing for the creation of a more complete
   replica of this [19]surprising ancient machine.

                     Tomorrow's picture: surround orion
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    Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell
                                 ([34]UMCP)
          NASA Official: Phillip Newman [35]Specific rights apply.
              [36]NASA Web Privacy Policy and Important Notices
                A service of: [37]ASD at [38]NASA / [39]GSFC
                           & [40]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2103/antikythera_wikipedia_1036.jpg
   3. https://creativecommons.org/licenses/by-sa/3.0/deed.en
   4. https://commons.wikimedia.org/wiki/User:Marsyas
   5. https://commons.wikimedia.org/wiki/File:NAMA_Machine_d%27Anticyth%C3%A8re_1.jpg
   6. https://en.wikipedia.org/wiki/Antikythera_mechanism
   7. https://en.wikipedia.org/wiki/Computer#Pre-20th_century
   8. https://www.smithsonianmag.com/history/decoding-antikythera-mechanism-first-computer-180953979/
   9. https://en.wikipedia.org/wiki/Greece
  10. http://img.gawkerassets.com/img/183lbg3rnl5w2jpg/original.jpg
  11. https://science.nasa.gov/ems/11_xrays
  12. https://youtu.be/RLPVCJjTNgk
  13. https://youtu.be/tmNuG15cqNw?t=410
  14. https://apod.nasa.gov/apod/ap190120.html
  15. https://apod.nasa.gov/apod/ap170912.html
  16. http://www.antikythera-mechanism.gr/
  17. https://youtu.be/UpLcnAIpVRA
  18. https://www.nature.com/articles/s41598-021-84310-w
  19. https://www.bbc.com/news/science-environment-56377567
  20. https://apod.nasa.gov/apod/ap210320.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.nasa.gov/apod.rss
  27. https://apod.nasa.gov/apod/lib/edlinks.html
  28. https://apod.nasa.gov/apod/lib/about_apod.html
  29. http://asterisk.apod.com/discuss_apod.php?date=210321
  30. https://apod.nasa.gov/apod/ap210322.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://astrophysics.gsfc.nasa.gov/
  38. https://www.nasa.gov/
  39. https://www.nasa.gov/centers/goddard/
  40. http://www.mtu.edu/