Antikythera Mechanism helped Greeks set Olympic schedule

Archaeologists had long known the Antikythera Mechanism, a bronze relic pulled from a Roman shipwreck, had been an astronomical calculator used by the ancient Greeks to predict phases of the moon and planets.

Now, a study out Wednesday shows the mechanism, which is at least 2,100 years old, also revealed the timing of the Greek Olympics, kept tabs on the local calendar and was used for eclipse predictions, making the device surprisingly practical.

"Nobody expected a device actually linking the cycles of the heavens to the very mundane Greek games," says historian Alexander Jones of New York University, one of the authors of the study in the journal Nature. "It was a complete surprise that means we are going to have to think hard about the point of such devices for the ancients."

The badly corroded mechanism was uncovered by sponge divers in 1901 and resides at the National Archaeological Museum of Athens. Scholarly interest has grown over the last five decades, most recently with the 2006 release of the first X-ray analysis.

The latest study improves on the earlier work, which found the hand-size device held 30 bronze gearwheels marked with instructions for calculating solar cycles. X-ray images of the mechanism's seven large and 75 small fragments reveal a dial predicting when Olympic games, which began with the first new moon after the summer solstice, should be held every four years.

The new analysis also finds on the mechanism a local calendar tied to Corinth and its colony, Syracuse, home of Archimedes, who died in a 212 B.C. siege after authoring a now-lost treatise on astronomical devices.

"The Corinthian month names is the most exciting piece of news for the mechanism since its identification as an astronomical device," says classicist Reviel Netz of Stanford University.

Most likely, the Antikythera Mechanism followed Archimedes' design, Netz says.

The Metonic calendar inscribed on the mechanism, which displayed the workings of the heavens such as eclipses and lunar phases to viewers when the gears turned, surprises historians who considered it too sophisticated for local calendars in the Greek world. The calendar followed a 19-year cycle of lunar months, adding extra days and months to track the seasons.

Archaeologists earlier considered the island of Rhodes, known in antiquity for intricate astronomical devices, the origin of the mechanism, which was found in wreckage of a Roman treasure ship laden with war booty.

"Now we have a bit of a mystery," Jones says.

The Corinth link implies a more widespread use of such devices among the wealthy who sponsored the ancient Greek games, he says.

"The mechanism just blows away our ideas of what technology could do at the time. It was very sophisticated."