Details of a 2,000-year-old Moon "computer" unveiled

The delicate workings at the heart of a 2000-year-old analogue computer have been revealed by scientists

The new research shows the following:

* The device was built between 150 to 100 B.C., somewhat earlier than the previously thought. The shipwreck took place about 65 B.C. The date is significant, as is the assumption (based on some circumstantial evidence) that the ship, traveling a busy sea route, was heading to Rome from Rhodes, where one of the greatest of Greek astronomers, Hipparchus, lived and worked from about 140 to 120 B.C. Researchers speculate that he or one of this students could have influenced the design, and possibly the building, of part of the mechanism.

* One especially remarkable arrangement of gears creates an anomalous motion for the moon, simulating visually the mathematics created by Hipparchus to account for moon's observed, irregular orbit around the Earth.

* One of the two back spiral dials is now shown to simulate what's called the Saros eclipse cycle, in which a given solar or lunar eclipse will be repeated 223 lunar months later.

* The second back spiral dial is now confirmed to have 235 teeth, demonstrating it simulates the Metonic lunar cycle, which over 19 years (235 lunar months), represents the return of the moon to the same phase on the same date in the year.

* Researchers now believe the device had 37 gear wheels; seven of those are deduced from the now more-visible details of the surviving wheels and from the new understanding of their relationships and functions.

* Researchers agree with Wright's speculation that some of the missing gears were likely used to simulate the movement of the known planets, making the Antikythera Mechanism one of the earliest and most complex planetariums.

The Nature article suggests that the new research will lead to a sea-change in scientific and historic understanding of the development and transmission of technology. Some suggest the Antikythera Mechanism represents a sustained development of sophisticated mechanical skills that took years, even decades to develop. Such a tradition would naturally have lead to other devices of somewhat similar complexity being developed, and now lost.

But were the skills lost? Or did they fade from view as Rome rose to its height, to appear fleetingly and fragmentarily in Byzantium and the Islamic Caliphate? And possibly to reappear as Europeans began to translate some of the storehouse of Arabic documents that preserved a wealth of earlier Greek writings, which otherwise would have been lost?

The Research Project may provide ongoing data to such explorations, with its plan to create a massive online database for ongoing study of the Antikythera Mechanism and the world, and most of all, the minds that produced it.

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