                        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.

                                 2021 June 7

                         A Bright Nova in Cassiopeia
                    Image Credit & Copyright: Chuck Ayoub

   Explanation: What's that new spot of light in Cassiopeia? A nova.
   Although novas occur frequently throughout the universe, this nova,
   known as Nova Cas 2021 or V1405 Cas, became so unusually bright in the
   skies of Earth last month that it was visible to the unaided eye. Nova
   Cas 2021 first brightened in mid-March but then, unexpectedly, became
   even brighter in mid-May and remained quite bright for about a week.
   The nova then faded back to early-May levels, but now is slightly
   brightening again and remains visible through binoculars. Identified by
   the arrow, the nova occurred toward the constellation of Cassiopeia,
   not far from the Bubble Nebula. A nova is typically caused by a
   thermonuclear explosion on the surface of a white dwarf star that is
   accreting matter from a binary-star companion -- although details of
   this outburst are currently unknown. Novas don't destroy the underlying
   star, and are sometimes seen to recur. The featured image was created
   from 14 hours of imaging from Detroit, Michigan, USA. Both professional
   and amateur astronomers will likely continue to monitor Nova Cas 2021
   and hypothesize about details of its cause.

                      Tomorrow's picture: Jupiter happy
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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