                        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.

                               2022 January 2

                    Quadruple Lunar Halo Over Winter Road
                    Image Credit & Copyright: Dani Caxete

   Explanation: Sometimes falling ice crystals make the atmosphere into a
   giant lens causing arcs and halos to appear around the Sun or Moon. One
   Saturday night in 2012 was just such a time near Madrid, Spain, where a
   winter sky displayed not only a bright Moon but four rare lunar halos.
   The brightest object, near the top of the featured image, is the Moon.
   Light from the Moon refracts through tumbling hexagonal ice crystals
   into a somewhat rare 22-degree halo seen surrounding the Moon.
   Elongating the 22-degree arc horizontally is a more rare circumscribed
   halo caused by column ice crystals. Even more rare, some moonlight
   refracts through more distant tumbling ice crystals to form a (third)
   rainbow-like arc 46 degrees from the Moon and appearing here just above
   a picturesque winter landscape. Furthermore, part of a whole 46-degree
   circular halo is also visible, so that an extremely rare -- especially
   for the Moon -- quadruple halo was captured. Far in the background is a
   famous winter skyscape that includes Sirius, the belt of Orion, and
   Betelgeuse -- visible between the inner and outer arcs. Halos and arcs
   typically last for minutes to hours, so if you do see one there should
   be time to invite family, friends or neighbors to share your unusual
   lensed vista of the sky.

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

