The Antikythera mechanism (/ˌæntɨkɨˈθɪərə/ ant-i-ki-theer-ə or /ˌæntɨˈkɪθərə/ ant-i-kith-ə-rə) is an ancient analog computer designed to predict astronomical positions and eclipses. It was recovered in 1900–01 from the Antikythera wreck, a shipwreck off the Greek island of Antikythera. The computer’s construction has been attributed to the Greeks and dated to the early 1st century BC. Technological artifacts approaching its complexity and workmanship did not appear again until the 14th century, when mechanical astronomical clocks began to be built in Western Europe.
The mechanism was housed in a wooden box about 340 × 180 × 90 mm in size and comprised 30 bronze gears (although more could have been lost). The largest gear, clearly visible in fragment A, was about 140 mm in diameter and had 223 teeth. The mechanism’s remains were found as 82 separate fragments of which only seven contain any gears or significant inscriptions.
The Antikythera mechanism is kept at the National Archaeological Museum of Athens. It is now displayed at the temporary exhibition about the Antikythera Shipwreck, accompanied by reconstructions made by Ioannis Theofanidis, Derek de Solla Price, Michael Wright, the Thessaloniki University and Dionysios Kriaris. Other reconstructions are on display at the American Computer Museum in Bozeman, Montana, at the Children’s Museum of Manhattan in New York, at Astronomisch-Physikalisches Kabinett in Kassel, Germany, and at the Musée des Arts et Métiers in Paris.