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.

                               2019 August 17

                      1901 Photograph: The Orion Nebula
       Image Credit: George Ritchey, Yerkes Observatory - Digitization
                             Project: W. Cerny,
   R. Kron, Y. Liang, J. Lin, M. Martinez, E. Medina, B. Moss, B. Ogonor,
                  M. Ransom, J. Sanchez (Univ. of Chicago)

   Explanation: By the turn of the 20th century advances in photography
   contributed an important tool for astronomers. Improving photographic
   materials, long exposures, and new telescope designs produced
   astronomical images with details not visible at the telescopic eyepiece
   alone. Remarkably recognizable to astrophotographers today, this
   stunning image of the star forming Orion Nebula was captured in 1901 by
   American astronomer and telescope designer George Ritchey. The original
   glass photographic plate, sensitive to green and blue wavelengths, has
   been digitized and light-to-dark inverted to produce a positive image.
   His hand written notes indicate a 50 minute long exposure that ended at
   dawn and a reflecting telescope aperture of 24 inches masked to 18
   inches to improve the sharpness of the recorded image. Ritchey's plates
   from over a hundred years ago preserve astronomical data and can still
   be used for exploring astrophysical processes.

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