                        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 April 29

                        Apollo 17: The Crescent Earth
            Image Credit: Apollo 17, NASA; Restoration - Toby Ord

   Explanation: Our fair planet sports a curved, sunlit crescent against
   the black backdrop of space in this stunning photograph. From the
   unfamiliar perspective, the Earth is small and, like a telescopic image
   of a distant planet, the entire horizon is completely within the field
   of view. Enjoyed by crews on board the International Space Station,
   only much closer views of the planet are possible from low Earth orbit.
   Orbiting the planet once every 90 minutes, a spectacle of clouds,
   oceans, and continents scrolls beneath them with the partial arc of the
   planet's edge in the distance. But this digitally restored image
   presents a view so far only achieved by 24 humans, Apollo astronauts
   who traveled to the Moon and back again between 1968 and 1972. The
   original photograph, AS17-152-23420, was taken by the homeward bound
   crew of Apollo 17, on December 17, 1972. For now it's the last picture
   of Earth from this planetary perspective taken by human hands.

                     - NASA Remembers Michael Collins -
                     Tomorrow's picture: pixels in 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
                             & Michigan Tech. U.

