                        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 24

                       Rigel and the Witch Head Nebula
                   Image Credit & Copyright: José Mtanous

   Explanation: By starlight this eerie visage shines in the dark, a
   crooked profile evoking its popular name, the Witch Head Nebula. In
   fact, this entrancing telescopic portrait gives the impression that the
   witch has fixed her gaze on Orion's bright supergiant star Rigel. More
   formally known as IC 2118, the Witch Head Nebula spans about 50
   light-years and is composed of interstellar dust grains reflecting
   Rigel's starlight. The blue color of the Witch Head Nebula and of the
   dust surrounding Rigel is caused not only by Rigel's intense blue
   starlight but because the dust grains scatter blue light more
   efficiently than red. The same physical process causes Earth's daytime
   sky to appear blue, although the scatterers in Earth's atmosphere are
   molecules of nitrogen and oxygen. Rigel, the Witch Head Nebula, and gas
   and dust that surrounds them lie about 800 light-years away.

                       Tomorrow's picture: open space
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