---
title: "Antikythera mechanism"
chunk: 4/12
source: "https://en.wikipedia.org/wiki/Antikythera_mechanism"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:38:28.502947+00:00"
instance: "kb-cron"
---

ΠΑΧΩΝ (Pashons)
ΠΑΥΝΙ (Payni)
ΕΠΙΦΙ (Epiphi)
The other months have been reconstructed; some reconstructions of the mechanism omit the five days of the Egyptian intercalary month. The Zodiac dial contains Greek inscriptions of the members of the zodiac, which is believed to be adapted to the tropical month version rather than the sidereal:

ΚΡΙΟΣ (Krios [Ram], Aries)
ΤΑΥΡΟΣ (Tauros [Bull], Taurus)
ΔΙΔΥΜΟΙ (Didymoi [Twins], Gemini)
ΚΑΡΚΙΝΟΣ (Karkinos [Crab], Cancer)
ΛΕΩΝ (Leon [Lion], Leo)
ΠΑΡΘΕΝΟΣ (Parthenos [Maiden], Virgo)
ΧΗΛΑΙ (Chelai [Scorpio's Claw or Zygos], Libra)
ΣΚΟΡΠΙΟΣ (Skorpios [Scorpion], Scorpio)
ΤΟΞΟΤΗΣ (Toxotes [Archer], Sagittarius)
ΑΙΓΟΚΕΡΩΣ (Aigokeros [Goat-horned], Capricorn)
ΥΔΡΟΧΟΟΣ (Hydrokhoos [Water carrier], Aquarius)
ΙΧΘΥΕΣ (Ichthyes [Fish], Pisces)
Also on the zodiac dial are single characters at specific points (see reconstruction at ref). They are keyed to a parapegma, a precursor of the modern day almanac inscribed on the front face above and beneath the dials. They mark the locations of longitudes on the ecliptic for specific stars. The parapegma above the dials reads (square brackets indicate inferred text):

The parapegma beneath the dials reads:

At least two pointers indicated positions of bodies upon the ecliptic. A lunar pointer indicated the position of the Moon, and a mean Sun pointer was shown, perhaps doubling as the current date pointer. The Moon position was not a simple mean Moon indicator which would indicate movement uniformly around a circular orbit; rather, it approximated the acceleration and deceleration of the Moon's elliptical orbit, through the earliest extant use of epicyclic gearing.
It also tracked the precession of the Moon's elliptical orbit around the ecliptic in an 8.88 year cycle. The mean Sun position is, by definition, the current date. It is speculated that since significant effort was taken to ensure the position of the Moon was correct, there was likely to have also been a "true sun" pointer in addition to the mean Sun pointer, to track the elliptical anomaly of the Sun (the orbit of Earth around the Sun), but there is no evidence of it among the fragments found. Similarly, neither is there the evidence of planetary orbit pointers for the five planets known to the Greeks among the fragments. But see Proposed gear schemes below.
Mechanical engineer Michael Wright demonstrated there was a mechanism to supply the lunar phase in addition to the position. The indicator was a small ball embedded in the lunar pointer, half-white and half-black, which rotated to show the phase (new, first quarter, half, third quarter, full, and back). The data to support this function is available given the Sun and Moon positions as angular rotations; essentially, it is the angle between the two, translated into the rotation of the ball. It requires a differential gear, a gearing arrangement that sums or differences two angular inputs.

==== Rear face ====

In 2008, scientists reported new findings in Nature showing the mechanism not only tracked the Metonic calendar and predicted solar eclipses, but also calculated the timing of panhellenic athletic games, such as the ancient Olympic Games. Inscriptions on the instrument closely match the names of the months that are used on calendars from Epirus in northwestern Greece and with the island of Corfu, which in antiquity was known as Corcyra.
On the back of the mechanism, there are five dials: the two large displays, the Metonic and the Saros, and three smaller indicators, the so-called Olympiad Dial, which has been renamed the Games dial as it did not track Olympiad years (the four-year cycle it tracks most closely is the Halieiad), the Callippic, and the exeligmos.
The Metonic dial is the main upper dial on the rear of the mechanism. The Metonic cycle, defined in several physical units, is 235 synodic months, which is very close (to within less than 13 one-millionths) to 19 tropical years. It is therefore a convenient interval over which to convert between lunar and solar calendars. The Metonic dial covers 235 months in five rotations of the dial, following a spiral track with a follower on the pointer that keeps track of the layer of the spiral. The pointer points to the synodic month, counted from new moon to new moon, and the cell contains the Corinthian month names.

ΦΟΙΝΙΚΑΙΟΣ (Phoinikaios)
ΚΡΑΝΕΙΟΣ (Kraneios)
ΛΑΝΟΤΡΟΠΙΟΣ (Lanotropios)
ΜΑΧΑΝΕΥΣ (Machaneus, "mechanic", referring to Zeus the inventor)
ΔΩΔΕΚΑΤΕΥΣ (Dodekateus)
ΕΥΚΛΕΙΟΣ (Eukleios)
ΑΡΤΕΜΙΣΙΟΣ (Artemisios)
ΨΥΔΡΕΥΣ (Psydreus)
ΓΑΜΕΙΛΙΟΣ (Gameilios)
ΑΓΡΙΑΝΙΟΣ (Agrianios)
ΠΑΝΑΜΟΣ (Panamos)
ΑΠΕΛΛΑΙΟΣ (Apellaios)
Thus, setting the correct solar time (in days) on the front panel indicates the current lunar month on the back panel, with resolution to within a week or so.
Based on the fact that the calendar month names are consistent with all the evidence of the Epirote calendar and that the Games dial mentions the very minor Naa games of Dodona (in Epirus), it has been argued that the calendar on the mechanism is likely to be the Epirote calendar, and that this calendar was probably adopted from a Corinthian colony in Epirus, possibly Ambracia. It has been argued that the first month of the calendar, Phoinikaios, was ideally the month in which the autumn equinox fell, and that the start-up date of the calendar began shortly after the astronomical new moon of 23 August 205 BC.
The Games dial is the right secondary upper dial; it is the only pointer on the instrument that travels in an anticlockwise direction as time advances. The dial is divided into four sectors, each of which is inscribed with a year indicator and the name of two Panhellenic Games: the "crown" games of Isthmia, Olympia, Nemea, and Pythia; and two lesser games: Naa (held at Dodona) and the Halieia of Rhodes. The inscriptions on each one of the four divisions are: