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.

                              2020 December 17

                              Gemini's Meteors
                Image Credit & Copyright: Stefano Pellegrini

   Explanation: Taken over the course of an hour shortly after local
   midnight on December 13, 35 exposures were used to create this postcard
   from Earth. The composited night scene spans dark skies above the snowy
   Italian Dolomites during our fair planet's annual Geminid meteor
   shower. Sirius, alpha star of Canis Major and the brightest star in the
   night, is grazed by a meteor streak on the right. The Praesepe star
   cluster, also known as M44 or the Beehive cluster, itself contains
   about a thousand stars but appears as a smudge of light far above the
   southern alpine peaks near the top. The shower's radiant is off the top
   of the frame though, near Castor and Pollux the twin stars of Gemini.
   The radiant effect is due to perspective as the parallel meteor tracks
   appear to converge in the distance. As Earth sweeps through the dust
   trail of asteroid 3200 Phaethon, the dust that creates Gemini's meteors
   enters Earth's atmosphere traveling at about 22 kilometers per second.

                 Tomorrow's picture: December's diamond ring
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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