Main Antikythera mechanism fragment dated to the early 1^st century BCE.

When some storm-tossed sponge divers sought shelter in 1900 at the small Aegean island of Antikythera northwest of Crete, they thought they’d try to recoup something for their trouble and so sent a lone diver down to take a quick look around. The diver re-surfaced raving about ‘dead bodies’ on the sea floor. Further dives determined that they’d stumbled upon an ancient shipwreck and that the ‘bodies’ the initial diver had seen were instead statues strewn about on the bottom.

Realising that they had struck archaeological ‘gold’, they began salvaging as much as they could bring up from the wreck. Salvage continued over the next two years. Amongst the beautiful statuary and amphorae were found a few fragments of a curious machine-like artifact (see picture above) which was badly corroded and completely encrusted in two millennia of oxidation, debris and sea moss. The finds were returned to Athens where the statuary, much of it of exceptional artistic quality, along with the mystery ‘device’ were turned over to the Greek National Archaeological Museum…

For decades, the mysterious Antikythera ‘mechanism’ languished as a curiosity. One could see it was a complex gear-driven ‘clockwork’ of some kind, but what it was or what it was for remained elusive… until physicist Derek Price became interested in what he thought might be an astronomical ‘clock’. In the 1950′s, Price advanced the theory that the device was in fact a sort of analogue computer for predicting the positions of the Sun, Moon and planets over extended periods of time. X-ray photography revealed more details of an extremely complex internal gear mechanism, but its true purpose remained unproven.

More than a century after it was found, advanced computer tomography (CT scans) finally showed sufficient detail to make a reliable reconstruction possible. Based largely on Dr. Price’s work and the CT images, the Antikythera mechanism was functionally reproduced, albeit in a less compact form than the original:

2007 Antikythera reconstruction (left) and schematic gear mechanism detail (right)

Not only does this remarkable machine accurately track the positions of the planets, even including their apparent ‘retrograde motions’*, making it a sort of ‘orrery’, it tracks the Moon and its phases as well. Using the 18 year ‘Saros’ and the 19 year ‘Metonic’ cycles discovered by the Babylonians, the Antikythera mechanism could even accurately predict solar and lunar eclipses!

A 4 year cycle was also found which didn’t seem to correspond to any astronomical event. It turned out to measure the quadrennial period of the Greek Olympiads!

Europe’s clockmakers would not approach the accuracy of the Antikythera device until the 15^th-16^th centuries. The fact of dozens of individually hand-ground gears all meshing with mathematical precision more than a millennium prior is still hard to believe! Whatever their current economic woes, those Greeks were smart sons of bitches! (and no, it’s not something the ‘ancient aliens’ left behind!)

Wikipedia: The Antikythera Mechanism:

Professor Michael Edmunds of Cardiff University, who led the most recent 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.”

Here’s a pretty good documentary that goes into further details:
YouTube: NatGeo: Star Clock B.C.

another reconstruction of the Antikythera device

* The ‘retrograde motion’ (especially of Mars’ orbit) is an illusion produced as the faster inner orbit of Earth ‘catches up with and passes’ Mars ‘on the inside lane’. This was the source of Ptolemy’s later (brilliant but incorrect) ‘epicycles’ to explain the planets’ apparent motions.