[color="Blue"]After a century of study, scientists have unlocked the secrets of a mysterious 2,100-year-old device known as the "Antikythera mechanism," showing it to be a complex and uncannily accurate astronomical computer. The mechanism, recovered in more than 80 highly corroded fragments from a sunken Roman ship, could predict the positions of the sun and planets, show the location of the moon and even forecast eclipses. The international team of scientists reported today that the device, the earliest known example of an arrangement of gear wheels, shows a technological sophistication that was not seen again until clockwork mechanisms were introduced in the 14th century. The results "imply that Greek technology was much more advanced in this area than was previously thought," said the team's leader, physicist Mike G. Edmunds of Cardiff University, United Kingdom. "If they could do this, what else could they do?" An even bigger question, according to science historian Francois Charette of Ludwig-Maximilians University of Munich, Germany, is why the technology vanished for more than 1,400 years before reappearing in a less advanced form. "Much of the mind-boggling technological sophistication available in some parts of the Hellenistic and Greco-Roman world was simply not transmitted further," he wrote in an editorial accompanying the team's report in the journal Nature.

Discovered in 1901
The device was found in 1901 by sponge divers in 120 feet of water off the coast of the Greek island of Antikythera. The site was on a major trade route between Rhodes and Rome.
Coins on the ship suggest it sank shortly after 85 B.C. The new study suggests that the Antikythera mechanism predates the sinking by 15 to 20 years. Edmunds' team brought a 7.5-ton X-ray tomography machine — similar to that used to perform CT scans on human patients — into the National Archeological Museum in Athens to examine the fragments in greater detail than was possible before. They were able to image the bronze gears more clearly and double the number of deciphered inscriptions on the casing. They concluded the device contained 37 separate gears, about 30 of which still survive. Two dials on the front show the zodiac and a calendar of the days of the year that can be adjusted for leap years, while metal pointers show the positions in the zodiac of the sun, moon and five planets known in antiquity. Two spiral dials on the back show the cycles of the moon and predict eclipses. By turning the gears with a hand crank, the user could select a specific day in the past or future and observe the positions of the heavenly objects on that day. The device was most likely used to indicate the beginning and end of growing seasons, to mark religious holidays and other significant events.

Hipparchus' influence
The identity of the maker will probably remain a mystery — there is no signature apparent on the device. But the astronomical information incorporated in the gears clearly is based on the calculations of the Greek astronomer Hipparchus, who worked on Rhodes from about 140 B.C. to about 120 B.C. Subsequently, the philosopher Posidonius established an astronomy school incorporating Hipparchus' ideas. Cicero, the Roman lawyer and consul, later wrote that Posidonius had made an instrument "which at each revolution reproduces the same motions of the sun, the moon and the five planets that take place in the heavens every day and night." Historians have dismissed Cicero's words as extravagant or mythic, but the discoveries suggest he may have been correct.

Source: http://www.chron.com/disp/story.mpl/front/4368145.html