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 February 24

                  Moon Corona, Halo, and Arcs over Manitoba
                   Image Credit & Copyright: Brent Mckean

   Explanation: Yes, but could you get to work on time if the Moon looked
   like this? As the photographer was preparing to drive to work,
   refraction, reflection, and even diffraction of moonlight from millions
   of falling ice crystals turned the familiar icon of our Moon into a
   menagerie of other-worldly halos and arcs. The featured scene was
   captured with three combined exposures two weeks ago on a cold winter
   morning in Manitoba, Canada. The colorful rings are a corona caused by
   quantum diffraction by small drops of water or ice near the direction
   of the Moon. Outside of that, a 22-degree halo was created by moonlight
   refracting through six-sided cylindrical ice crystals. To the sides are
   moon dogs, caused by light refracting through thin, flat, six-sided ice
   platelets as they flittered toward the ground. Visible at the top and
   bottom of the 22-degree halo are upper and lower tangent arcs, created
   by moonlight refracting through nearly horizontal hexagonal ice
   cylinders. A few minutes later, from a field just off the road to work,
   the halo and arcs had disappeared, the sky had returned to normal --
   with the exception of a single faint moon dog.

                  Tomorrow's picture: Jupiter-sized magnet
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