                        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 October 25

                  Gone in 60 Seconds: A Green Flash Sunset
                    Video Credit & Copyright: Tengyu Cai

   Explanation: In 60 seconds, this setting Sun will turn green. Actually,
   the top of the Sun already appears not only green, but wavey -- along
   with all of its edges. The Sun itself is unchanged -- both effects are
   caused by looking along hot and cold layers in Earth's atmosphere. The
   unusual color is known as a green flash and occurs because these
   atmospheric layers not only shift background images but disperse colors
   into slightly different directions, like a prism. The featured video
   was captured earlier this month off the coast of Hawaii, USA. After
   waiting those 60 seconds, at the video's end, the upper part of the Sun
   seems to hover alone in space, while turning not only green, but blue.
   Then suddenly, the Sun appears to shrink to nothing -- only to return
   tomorrow.

                       Tomorrow's picture: open space
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

