This Day in Tech History

On This Day . . .

Amazing Computer . . . From 2000 Years Ago!

OLYMPUS DIGITAL CAMERAMay 17, 1902: Greek Archaeologist, Valerios Stais Discovers the Antikythera Mechnism…

…an ancient mechanical analog computer.  This 2000-year-old computer demonstrates remarkable engineering and astronomical precision.  Its wheels and gears create a portable orrery of the sky that predicted star and planet locations as well as lunar and solar eclipses.

Stais was a Greek archaeologist. He studied medicine but switched to archaeology and became the director of the National Archaeological Museum of Athens. He led excavations in several areas including the Greek island of Antikythera where this mechanism was found. The mechanism was found and recovered from the Antikythera wreck which itself was discovered by sponge divers. The ship was holding several statues as well as this early analog computer.

Photo of Valerios Stais in diving suit in 1902

Photo of Valerios Stais in diving suit in 1902

Valerios Stais

Valerios Stais

At the time of the discovery, it was simply an unknown device. However, it contained many gears and was of sophistication on par with a 19th century Swiss clock. It was flawlessly made leading some to speculate that it was not the first of its kind. It is estimated it was constructed around 150-100 BC. All instructions are written in Koine Greek and may have been built in Rhodes by Posidonius. Others believe it may have originated in Corinth and might be connected with Archimedes.

Back of the mechanism

Back of the mechanism

On display at the National Archaeological Museum of Athens

On display at the National Archaeological Museum of Athens








The complex mechanism contains more than 30 gears. There is speculation it may have contained up to 72 gears. A date would have been selected using a crank which has been lost to us. The mechanism would then calculate the position of the Sun, Moon, or other astronomical information including the position of the known planets or wandering stars. It was built to position astronomical bodies in the celestial sphere and was based on a geocentric or Earth centered universe.

Computer generated illustration of the back panel

Computer generated illustration of the back panel

Professor Michael Edmunds of Cardiff University, who led a 2006 study of the mechanism, said:

This device is just extraordinary, the only thing of its kind. The design is beautiful, the astronomy is exactly right. The way the mechanics are designed just makes your jaw drop. Whoever has done this has done it extremely carefully … in terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa.

–        30 November 2006

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.

IMGP4073-s Antikythera_model_front_panel_Mogi_Vicentini_2007

The mechanism was operated by turning a small hand crank (now lost) which was linked via a crown gear to the largest gear (the 4 spoked gear visible on the front of fragment A (named b1)). This allowed setting of the date on the front dial. The action of turning the hand crank would also cause all interlocked gears within the mechanism to rotate, resulting in the calculation of the position of the Sun and Moon and other astronomical information, such as moon phases, eclipse cycles, and theoretically the locations of planets.


The mechanism is remarkable for the level of miniaturization and the complexity of its parts, which is comparable to that of 14th-century astronomical clocks. It has at least 30 gears, although Michael Wright has suggested that the Greeks of this period were capable of implementing a system with many more gears.

For an in depth look at this remarkable 2000 year old technology visit:

Amazing Technology and Craftsmanship


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