PC Wholesale's Guide to the Ancient Astronomical Computer

Photo courtesy of Flickr: Andrew Barclay

While the computer is a modern-day apparatus, its early predecessor dates back to the first century B.C. In 1901, an ancient astronomical computer named the Antikythera Mechanism was recovered from a shipwreck off the southern coast of Greece. The wreck was located near Antikythera, Greece, thus giving the astronomical device its name. Scientists have dated the mechanism to approximately 87 B.C., and its discovery shed new light on the knowledge possessed by the ancient Greeks. The Antikythera Mechanism was used as a means for predicting or determining astronomical positions. It contained gears within a box, and the user could turn a handle to control the gears. The device would point to astronomical dates that were used to determine when astronomical bodies would rise and set. The Antikythera Mechanism consists of 82 fragments; they are currently housed at the National Archaeological Museum of Athens.

The Antikythera Mechanism's gear system is the oldest known in human history. One of the most impressive facts about the mechanism is that it could accurately predict how the sky and its heavenly bodies would appear decades in advance. The mechanism could show the position of the sun and moon, eclipses, and lunar phases. Parts of the Antikythera Mechanism include the sun wheel, input wheel, calendar gear train, eclipse gear train, lunar anomaly platform, and the lunar anomaly eccentric couple. There were individual panels for each planet as well. The calendar display and eclipse prediction display made the back dial of the mechanism, and inscriptions were present on the dial. The gears would turn and align to the correct dates, making the mechanism the most intricate, yet accurate, computer of its time. When one thinks that this mechanism was used by the Greeks before the birth of Jesus, it's nearly impossible not to marvel at its mathematical complexity.

A group of divers discovered the mechanism, but it began to disintegrate as soon as it was lifted out of the water. Today, the mechanism is preserved at the National Archaeological Museum of Athens and a replica has been built to demonstrate its function. The discovery has intrigued scientists, mathematicians, and researchers worldwide. Twenty-first-century technology helped reveal further information about the Antikythera Mechanism, and high-powered photography showed there were inscription-like instructions present on the object. Scientists used the information in these inscriptions with the locations of astronomical objects and discovered the mechanism's purpose. Also interesting is that the mechanism reveals data or information on both the front and back of the unit. The front dial is large and features 365 days that coincide with the Egyptian solar calendar. Inside is a second circle that lines up with the zodiac. When the handle was turned, the points would line up with the zodiac and the solar calendar, revealing to the user the exact location of the sun and moon and the moon's phase.

The Antikythera Mechanism operated on the 19-year Metonic cycle devised by the Greek astronomer Meton of Athens. Many ancient calendars used the Metonic cycle, including the Babylonian, Chinese, Greek, and Hebrew calendars. The Metonic cycle was an accurate method for predicting the dates of eclipses and corresponded to 235 lunar months. Another dial would predict solar and lunar eclipses. Because the panels were connected through interlocking gears, when one configuration was determined, the other panel would reveal dates. This made it possible for the ancient Greeks to determine the date for solar and lunar eclipses accurately and quickly. Scientists have marveled that the ancient Greeks could create a device that interpreted complex data such as lunar cycles in such an efficient manner. For many laypeople, comparing the Antikythera Mechanism to a high-powered watch helps explain its mechanisms and accuracy.

Scientists continue to reveal information surrounding the Antikythera Mechanism, and the journal Nature reported in 2008 that evidence showed that the mechanism was used to determine the dates for the ancient Olympic Games. The information was revealed through further decoding of the inscriptions engraved on the piece. The dates for the Olympic Games were selected based upon their proximity to the full moon that occurred before the summer solstice began. Many expect more surprises will continue to verify the wisdom of the ancients and the sophistication used in the Antikythera Mechanism.

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