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 March 21
    The ancient Antikythera mechanism is shown, the oldest known orrery.

                          The Antikythera Mechanism
                 Image Credit & License: Marsyas, Wikipedia

   Explanation: No one knew that 2,000 years ago, the technology existed
   to build such a device. The Antikythera mechanism, pictured, is now
   widely regarded as the first computer. Found at the bottom of the sea
   aboard a decaying Greek ship, its complexity prompted decades of study,
   and even today some of its functions likely remain unknown. X-ray
   images of the device, however, have confirmed that a main function of
   its numerous clock-like wheels and gears is to create a portable,
   hand-cranked, Earth-centered, orrery of the sky, predicting future star
   and planet locations as well as lunar and solar eclipses. The corroded
   core of the Antikythera mechanism's largest gear is featured, spanning
   about 13 centimeters, while the entire mechanism was 33 centimeters
   high, making it similar in size to a large book. Recently, modern
   computer modeling of missing components is allowing for the creation of
   a more complete replica of this surprising ancient machine.

                     Tomorrow's picture: surround orion
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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.

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