The Antikythera Mechanism

Posted on December 6, 2006

The Antikythera Mechanism is an ancient calculator used to calculate astronomical positions. In 1900 the 2,000-year-old device was discovered a shipwreck off the Greek island of Antikythera, which is where the device gets its name. An article in Nature explains that new X-ray technology has found that the Antikythera Mechanism was far more advanced than previously thought. Jo Marchant, Nature's news editor, writes, "No earlier geared mechanism of any sort has ever been found. Nothing close to its technological sophistication appears again for well over a millennium, when astronomical clocks appear in medieval Europe. It stands as a strange exception, stripped of context, of ancestry, of descendants."

Nothing close matching its sophistication for nearly 1,000 years -- what became of the technology? How was such advanced technology lost to the world for ten centuries? The complexity of the ancient astronomical calculator raises so many interesting questions about our history. Marchant also writes about how the marvelous device has gone relatively unappreciated in archaeology: "Considering how remarkable it is, the Antikythera Mechanism has received comparatively scant attention from archaeologists or historians of science and technology, and is largely unappreciated in the wider world."

A group of scientists have been examing the Antikythera Mechanism in detail -- see the Antikythera Mechanism Research Project. With three-dimensional X-ray tomography and high-resolution surface imaging the complexity of the device was revealed including that the device had 30+ gears and was capable of precise astronomical measurements. You can see a photograph of the reconstruction of the device above. A Live Science article explains just how accurate the device was.

The new analysis reveals that the device's front dials [image] had pointers for the sun and Moon-called the "golden little sphere" and "little sphere," respectively-and markings which coincided with the zodiac and solar calendars. The back dials [image], meanwhile, appear to have been used for predicting solar and lunar eclipses [image].

The researchers also show that the device could mechanically replicate the irregular motions of the Moon, caused by its elliptical orbit around the Earth, using a clever design involving two superimposed gear-wheels, one slightly off-center, that are connected by a pin-and-slot device.

The team was also able to pin down the device's construction date more precisely. Radiocarbon dating suggested it was built around 65 BC, but newly revealed lettering on the machine indicate a slightly older construction date of 150 to 100 BC. The team's reconstruction also involves 37 gear wheels, seven of which are hypothetical.

The recent imaging also found that the device contains over 2,000 characters written in the Greek language. The Antikythera Mechanism Research Project plans to continue its in-depth research of the ancient calculator and report on any discoveries they make. More details in the Wikipedia entry which also highlights some ancient texts that may have been describing similar ancient devices.

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