                        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 September 3

                          NGC 7023: The Iris Nebula
                   Image Credit & Copyright: Satwant Kumar

   Explanation: These cosmic clouds have blossomed 1,300 light-years away,
   in the fertile starfields of the constellation Cepheus. Called the Iris
   Nebula, NGC 7023 is not the only nebula to evoke the imagery of
   flowers. Still, this deep telescopic image shows off the Iris Nebula's
   range of colors and symmetries, embedded in surrounding fields of
   interstellar dust. Within the Iris itself, dusty nebular material
   surrounds a hot, young star. The dominant color of the brighter
   reflection nebula is blue, characteristic of dust grains reflecting
   starlight. Central filaments of the reflection nebula glow with a faint
   reddish photoluminesence as some dust grains effectively convert the
   star's invisible ultraviolet radiation to visible red light. Infrared
   observations indicate that this nebula contains complex carbon
   molecules known as PAHs. The dusty blue petals of the Iris Nebula span
   about six light-years.

                      Tomorrow's picture: light-weekend
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