Fully Reconstructed Antikythera 3D Working Astronomical Computer Mechanism

01 / Reconstruction

The celestial displayBronze gearwork, wooden enclosure, concentric cosmos rings

Initializing native WebGL

WebGL is unavailable. Enable hardware acceleration in Chrome and reload. The complete mathematical engine, dial reader and gear laboratory remain available.

Drag to orbit · Wheel / pinch to zoom · Right-drag / two-finger drag to pan · Double-click to fit

Reconstructed appearance; internal layout is interpretive

02 / Read the instrument

The front and rear indications

Cosmos / zodiac

Sun / dateInner to outer: Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn

Equal 30° zodiac signs; geocentric longitude. Ring radii are visual organization, not astronomical distances.

Calendar / eclipse spirals

Pointers follow the spiral grooves. Their radial return is automated at the cycle boundary; the physical instrument required resetting the follower.

Current dial readings

Rear dial epochs are initially arbitrary: month 1 is assigned to the modern reference date. Set independent calendar and Saros offsets in Calibration before interpreting historical dates.

Lunar anomaly · pin and slot

This enlarged diagram shows the same exact geometric correction used by the engine. It is a local kinematic diagram, not a scale view of the entire assembly.

Saros eclipse register

Freeth 2014 Eclipse Year Model (EYM): a reconstructed plate pattern, not a forecast for the date above. Later work revises the associated inscription grouping. Η = solar possibility; Σ = lunar possibility. Select a month to drive the mechanism there.

Only marked cells

Cell	Indication	Lunar node offset	Solar node offset	Evidence status	Drive

Exeligmos hour correction

Engraved base hour (0–24)

A calculator for a supplied inscription reading, not a fabricated complete hour table. The default 1 is an example. Absolute times of missing glyphs are not recoverable with certainty.

Metonic civil calendar completion

The 12 named months are attested. This app uses a declared regularized completion for the missing placement of leap months and omitted days. It is kept separate from the uniform gear-driven month coordinate.

Cell	Cycle year	Month	Civil days	Status

03 / Arithmetic in metal

One input. Interconnected outputs.

Inspect train

The laboratory unfolds the ratios for readability. Paired wheels mesh; vertical connectors mean a shared axle. Planetary rates are relative to a carrier turning once per year. The 3D assembly is an interpretive spatial layout, not a manufacturing drawing.

Cycle engine

Output	Exact mechanism relation	Period with current year length	Status

Planetary motions

The long period relations constrain mean rates. Circular epicycles omit real orbital eccentricities, inclinations and perturbations; a precise gear ratio does not make the apparent longitude a precise ephemeris.

Model analysis / same mechanical equations

Find an astronomical configuration

This software measuring aid solves the ideal mechanism model. Results are not modern ephemerides or predictions of local visibility. Conjunctions refer to equal ecliptic longitude; stationary points refer to zero longitude velocity.

Body Event Reference Direction Count

Choose a configuration, then search from the current elapsed day.

Configuration	Model civil date	Julian Date	Equation residual	Drive

Go restores the calibration used for that result and pauses playback. A tiny equation residual measures numerical convergence, not historical or astronomical accuracy. Greatest elongation is available for Mercury and Venus; opposition is available for Mars, Jupiter and Saturn.

04 / Calibration bench

Choose the datum, preserve the ratios

All controls below affect the mathematical model. A change is applied only with “Apply calibration”. No original absolute epoch is asserted. Modern reference phases initialize the display; the rear calendars start from an arbitrary independent month 1.

Calibration notes / source / assumed epoch

Include attested lunar pin-and-slot variabilityInclude reconstructed solar anomaly (geometric ratio 1/24)

Go to civil date

Astronomical year Month Day Hour

Astronomical year 0 = 1 BCE; −204 = 205 BCE. No browser date parser is used. The calendar system is explicit and never switches automatically in 1582. Input dates label the elapsed time; they do not authenticate a historical reconstruction epoch.

05 / Reproducibility

Verification ledger

The checks below execute locally against the embedded engine. They test reference constants, independent geometry, cycle boundaries and numerical behavior. They cannot prove that a hypothetical lost assembly was the original one.

Check	Result	Evidence / residual

A Cosmos in Bronze