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 November 30

                            Cygnus Without Stars
                Image Credit & Copyright: Bowen James Cameron

   Explanation: The sky is filled with faintly glowing gas, though it can
   take a sensitive camera and telescope to see it. For example, this
   twelve-degree-wide view of the northern part of the constellation
   Cygnus reveals a complex array of cosmic clouds of gas along the plane
   of our Milky Way galaxy. The featured mosaic of telescopic images was
   recorded through two filters: an H-alpha filter that transmits only
   visible red light from glowing hydrogen atoms, and a blue filter that
   transmits primarily light emitted by the slight amount of energized
   oxygen. Therefore, in this 18-hour exposure image, blue areas are
   hotter than red. Further digital processing has removed the myriad of
   point-like Milky Way stars from the scene. Recognizable bright nebulas
   include NGC 7000 (North America Nebula), and IC 5070 (Pelican Nebula)
   on the left with IC 1318 (Butterfly Nebula) and NGC 6888 (Crescent
   Nebula) on the right -- but others can be found throughout the wide
   field.

                  Tomorrow's picture: star forming cluster
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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