                        Astronomy Picture of the Day

    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

                 Startrails over Beijing Ancient Observatory
                  Image Credit & Copyright: Jeff Dai (TWAN)

   Explanation: 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 Beijing Ancient Observatory
   site to enable them to accurately measure and track the positions of
   naked-eye stars and planets. Some of the large, ornate 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 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 armillary sphere. Compare
   this picture from the Beijing Ancient Observatory taken in September
   2023 to one taken in 1895.

                         Tomorrow's picture: moonset
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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