Greeks followed a celestial Olympics

Normal 0 false false false MicrosoftInternetExplorer4 Chalk up another Olympian feat to a mechanical gadget discovered more than a century ago in a 2,100-year-old shipwreck.

Scientists over the past decades have determined that the device was used to perform complex astronomical calculations, including the prediction of solar and lunar eclipses and the movement of the planets.

Known as the Antikythera mechanism, for the small Greek island near which sponge divers recovered it in 1901, the device is split into 82 fragments and is an agglomeration of disintegrating bronze gears and teeth, encrusted dials and hard-to-read inscriptions. Researchers have long been intrigued by both the gear teeth and inscriptions.

Using 3-D X-ray imaging to reveal more of the inscriptions on the device, researchers have now determined that the gadget charted the four-year cycle of the Olympics and the cycles of other ancient Greek games.

These results and other new findings “link the cycle of human institutions with the celestial cycles embedded in the mechanism’s gear-work,” says Tony Freeth of the Antikythera Mechanism Research Project in Cardiff, Wales, and Images First Ltd in London.

The first clue suggesting a link to the Greek games came when researchers deciphered the word “NEMEA” near a small subsidiary dial on the mechanism. This represents the Nemean games, part of the Olympiad cycle. Next, Freeth and his colleagues deciphered other names, including “ISTHMIA” for the games at Corinth, “PYTHIA” for the games at Delphi, and “OLYMPIA” for the Olympic games. Freeth, a filmmaker and mathematician, and his collaborators report the findings in the July 31 Nature.

The newly revealed inscriptions also identify 12 calendar month names on the back of the mechanism, showing a sophisticated 19-year calendar.

“The interpretation of the upper-back dial as a [calendar] dial is not new, but the authors have for the first time been able to recover all month names from the few heavily damaged remaining fragments of the 235 original labels,” notes François Charlotte, an independent researcher and scientific manuscript cataloguer at the Chester Beatty Library in Dublin, Ireland.

The paper provides the first concrete evidence for the use of a calendar scheme described by the Greek astronomer Geminos. In this system, months have 30 days with one day omitted every 64th day in order to have the correct average month length over a cycle of 19 years. “Historians of astronomy had until now doubted that this scheme had been actually used in civil life. But the evidence from the Antikythera mechanism now proves them wrong,” says Charlotte.

The team found that the names of the months correspond to those used in Corinth and suggest that the device may have originated in Syracuse, Sicily, then a Corinthian colony and the residence of Archimedes. Although the Antikythera mechanism was devised several decades after Archimedes’ death, its geographic location suggests a possible link to scientific instruments developed by the Greek scholar, Freeth’s team notes.

“Establishing a calendar is very tricky,” comments Diomidis Spinellis of the Athens University of Economics and Business. “One has to find a way to divide time into logical units of days and months that follow accurately the movements of the heavenly bodies,” he notes. Moreover, he adds, “An ideal calendar should work without requiring astronomers to intervene annually to align the calendar year with the tropical year, which determines the seasons.”

Such a calendar was employed by the Romans, but “new details uncovered on the operation of the Antikythera mechanism indicate that it may have been common for Greek civil calendars to follow the highly accurate [19-year] Metonic cycle by about 100 B.C.,” says Spinellis.

The findings further bolster the notion that the Antikythera mechanism is at least 1,000 years more advanced than any other known mechanical devices from the first century B.C.