The crank

years since the epoch0.0000

epoch set at

Travel jump to an eclipse or a year

eclipses

year

Eclipses

The Moon

the sky's libration

The Moon as the machine's phase ball has it, lit from where its Sun pointer stands; the face is the near side from NASA's LROC mosaic. The machine shows one face always. The real Moon rocks a few degrees each month, and the sky's libration turns the face to where it stood that day (astronomy-engine), under the machine's light.

The sky it tracks

Earth in the middle, the zodiac around it. Each body is drawn where its own pin-and-slot puts it, so the trail it leaves is the loop a Greek epicycle predicts, the geometry Ptolemy later refined: the outer planets loop backwards each time the Earth overtakes them. Verdigris ticks are the true sky; bronze ticks are what the machine shows. The strip beneath is the same motion unrolled, longitude against time: where a line steps backwards, that planet is in retrograde.

The front dial what every pointer reads

Against the real sky how far the pointers are from the truth

Truth from astronomy-engine (VSOP87/NOVAS, about an arcminute in the modern era) and NASA's Five Millennium Canon (Espenak & Meeus).

How each anomaly device was set: its pin turned to the phase that best matches the sky over ±1½ of its cycles around the epoch, as the maker would have set it on the day. The error that remains is the model's own: one epicycle cannot follow Mars's eccentric orbit, so Mars wanders most.

How accurate was it? error over the centuries, eclipses hit and missed

Pointer error against the ephemeris, sampled every day: each band is the swing within one year. The ±6.5° pin-and-slot removes most of the Moon's equation of centre; what is left in the band is evection and variation, which the machine does not model.

Saros glyphs (Freeth 2014 eclipse-year model) checked month by month against NASA's canon, from the epoch. A solar glyph counts as a hit if the eclipse was visible somewhere on Earth.

The back dials Metonic, Callippic, games, Saros, Exeligmos

The gear trains seventeen trains, as the papers write them

Choose a train to see it alone in the machine; choose it again to bring everything back. Gears in italic are reconstructed; the rest survive in the fragments.

Sources who this rests on

Who made it, and where, is not written on the bronze. The Halieia, a festival of Rhodes, on the games dial points to a Rhodian workshop, and the month names to a buyer in north-west Greece, perhaps Epirus (Iversen 2017); no maker is named, and this exhibit names none.

Reconstruction after Freeth, Higgon, Dacanalis, MacDonald, Georgakopoulou and Wojcik, A Model of the Cosmos in the ancient Greek Antikythera Mechanism, Scientific Reports 11:5821 (2021), CC BY 4.0, with the earlier AMRP papers (2006–2014). Epochs: Carman & Evans 2014; Voulgaris, Mouratidis & Vossinakis 2023.

Eclipses: NASA's Five Millennium Canon (Espenak & Meeus). Sky: astronomy-engine (Don Cross). Fragment A CT scan: Ashkan Pakzad, CC BY 4.0. The Moon's face: NASA's CGI Moon Kit (LROC), public domain. Rooms: Poly Haven HDRIs, CC0. Layout reference: Thomas Weibel, CC BY.

Every gear here is generated from one tooth table. The parapegma letters stand where Bitsakis and Jones place them: thirteen read on the zodiac scale of Fragment C, six from the numerals written after the parapegma lines, five restored at the sign boundaries; the eleven not read on the bronze are cut in a fainter ink, letters whose place is lost are not drawn, and the Saros glyph hours beyond the 15 surviving cells are schematic.

Version 1.0, September 2026. Built in Blender 5.1 and three.js.