Abstract
The ancient Greek astronomical calculating machine, known as the Antikythera Mechanism, predicted eclipses, based on the 223-lunar month Saros cycle. Eclipses are indicated on a four-turn spiral Saros Dial by glyphs, which describe type and time of eclipse and include alphabetical index letters, referring to solar eclipse inscriptions. These include Index Letter Groups, describing shared eclipse characteristics. The grouping and ordering of the index letters, the organization of the inscriptions and the eclipse times have previously been unsolved. A new reading and interpretation of data from the back plate of the Antikythera Mechanism, including the glyphs, the index letters and the eclipse inscriptions, has resulted in substantial changes to previously published work. Based on these new readings, two arithmetical models are presented here that explain the complete eclipse prediction scheme. The first model solves the glyph distribution, the grouping and anomalous ordering of the index letters and the structure of the inscriptions. It also implies the existence of lost lunar eclipse inscriptions. The second model closely matches the glyph times and explains the four-turn spiral of the Saros Dial. Together, these models imply a surprisingly early epoch for the Antikythera Mechanism. The ancient Greeks built a machine that can predict, for many years ahead, not only eclipses but also a remarkable array of their characteristics, such as directions of obscuration, magnitude, colour, angular diameter of the Moon, relationship with the Moon’s node and eclipse time. It was not entirely accurate, but it was an astonishing achievement for its era.
Highlights
In the autumn of 2005, a major data gathering operation on the Antikythera Mechanism was carried out by an Anglo-Greek team of academics in collaboration with the National Archaeological Museum in Athens and two advanced technology companies [1].Figure 1 shows the surviving remains of the Antikythera Mechanism, which are split into 82 fragments [1]
Previous research proposed a mathematical model for the distribution of the glyphs round the Saros Dial, which was consistent with the alphabetic index letters [4]
This model could not have been calculated in ancient Greece and it needed to be calibrated from a lunar eclipse 210 lunar months earlier: so it was not really plausible
Summary
In the autumn of 2005, a major data gathering operation on the Antikythera Mechanism was carried out by an Anglo-Greek team of academics in collaboration with the National Archaeological Museum in Athens and two advanced technology companies [1]. They are conserved in the National Archaeological Museum in Athens, Greece. Microfocus X-ray Computed Tomography (X-ray CT) [3] produces high-resolution 3D X-rays using a very small X-ray source. For details of these techniques, see Materials and Methods
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