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.

                               2023 December 2
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                 Startrails over Beijing Ancient Observatory
             Image Credit & [3]Copyright: [4]Jeff Dai ([5]TWAN)

   Explanation: [6]You can take a subway ride to visit this observatory in
   Beijing, China but you won't find any telescopes there. Starting in the
   1400s astronomers erected devices at the [7]Beijing Ancient Observatory
   site to enable them to accurately measure and track the positions of
   [8]naked-eye stars and planets. Some of the large, ornate
   [9]astronomical instruments are still standing. You can even see stars
   from the star observation platform today, but now only the very
   brightest celestial beacons are visible [10]against the city lights. In
   this time series of exposures from a camera fixed to a tripod to record
   graceful arcing startrails, the brightest trail is actually the Moon.
   Its broad arc is seen behind the ancient observatory's brass
   [11]armillary sphere. Compare this picture from the Beijing Ancient
   Observatory taken in September 2023 to [12]one taken in 1895.

                         Tomorrow's picture: moonset
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    Authors & editors: [24]Robert Nemiroff ([25]MTU) & [26]Jerry Bonnell
                                 ([27]UMCP)
          NASA Official: Phillip Newman [28]Specific rights apply.
              [29]NASA Web Privacy Policy and Important Notices
                A service of: [30]ASD at [31]NASA / [32]GSFC,
                         [33]NASA Science Activation
                           & [34]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2312/StartrailsBeijingAncientObservatory-3.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://twanight.org/profile/jeff-dai/
   5. https://www.twanight.org/
   6. https://asd.gsfc.nasa.gov/blueshift/index.php/2010/08/20/maggies-blog-beijings-ancient-observatory/
   7. https://www.bjp.org.cn/en/Beijing Ancient Observatory/History of the Observatory/index.shtml
   8. https://science.nasa.gov/skywatching/
   9. https://www.bjp.org.cn/en/Beijing Ancient Observatory/Astronomical instruments/list.shtml
  10. https://apod.nasa.gov/apod/ap110716.html
  11. https://en.wikipedia.org/wiki/Armillary_sphere
  12. https://apod.nasa.gov/apod/ap980506.html
  13. https://apod.nasa.gov/apod/ap231201.html
  14. https://apod.nasa.gov/apod/archivepix.html
  15. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  16. https://apod.nasa.gov/apod/lib/aptree.html
  17. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  18. https://apod.nasa.gov/apod/calendar/allyears.html
  19. https://apod.nasa.gov/apod.rss
  20. https://apod.nasa.gov/apod/lib/edlinks.html
  21. https://apod.nasa.gov/apod/lib/about_apod.html
  22. http://asterisk.apod.com/discuss_apod.php?date=231202
  23. https://apod.nasa.gov/apod/ap231203.html
  24. http://www.phy.mtu.edu/faculty/Nemiroff.html
  25. http://www.phy.mtu.edu/
  26. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  27. http://www.astro.umd.edu/
  28. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  29. https://www.nasa.gov/about/highlights/HP_Privacy.html
  30. https://astrophysics.gsfc.nasa.gov/
  31. https://www.nasa.gov/
  32. https://www.nasa.gov/centers/goddard/
  33. https://science.nasa.gov/learners
  34. http://www.mtu.edu/