Scientists have been working for more than a century to decipher the Antikythera Mechanism, which is a 2,000-year-old device used by ancient Greeks to calculate astronomical positions.

Now researchers at University College London (UCL) believe they have solved the mystery of the ‘world’s oldest computer’ by building a digital replica with a working gear system at the front – the piece that has eluded the scientific community since 1901.

Using a combination of X-ray images and ancient Greek mathematical analysis, the team decoded the design of the front gear to match physical evidence and inscriptions etched into the bronze.

The digital result shows a celestial dome representing Earth that is surrounded by the moon phases, the sun, Zodiac constellations, and rings for Mercury, Venus, Mars, Jupiter, and Saturn.

Lead author Professor Tony Freeth (UCL Mechanical Engineering) explained: ‘Ouris is the first model that conforms to all the physical evidence and matches the descriptions in the scientific inscriptions engraved on the Mechanism itself.

‘The Sun, Moon, and planets are displayed in an impressive tour de force of ancient Greek brilliance.’

Researchers believe they have solved the mystery of the ‘world’s oldest computer’ by building a digital replica with a working gear system at the front – the computer dome is Earth surrounded by the moon phases, the sun, and the positions of Mercury, Venus, Mars, Jupiter, and Saturn.

In 1901, divers looking for sponges off the coast of Antikythera, a Greek island in the Aegean Sea, stumbled upon a Roman-era shipwreck that held the highly sophisticated astronomical calculator.

The Antikythera Mechanism has since captivated the scientific community and the world with wonder but has also sparked more than a century-long investigation into how an ancient civilization fashioned such an incredibly advanced device.

The calculator’s gears and face form the motions of the planets and sun, phases of the lunar calendar, and positions of Zodiac constellations, along with special Earth events like the Olympic Games.

At the time, there were only five known planets and the Greeks positioned them Earth as the center of the universe, which was all taken into account by UCL when making their model.

Th𝚎 t𝚎𝚊m 𝚞s𝚎𝚍 𝚊 c𝚘m𝚋in𝚊ti𝚘n 𝚘𝚏 X-𝚛𝚊𝚢 im𝚊𝚐𝚎s 𝚊n𝚍 𝚊nci𝚎nt G𝚛𝚎𝚎k m𝚊th𝚎m𝚊tic𝚊l 𝚊n𝚊l𝚢sis t𝚘 𝚋𝚞il𝚍 its 𝚍i𝚐it𝚊l 𝚛𝚎𝚙lic𝚊

In 1901, divers looking for sponges off the coast of Antikythera, a Greek island in the Aegean Sea, stumbled upon an extraordinary archaeological calcification. Only about one-third of the Mechanism has survived, and is split into 82 fragments.

Researchers say the mechanism may have displayed the movement of the sun, moon and the planets Mercury, Venus, Mars, Jupiter, and Saturn on concentric rings.

The team began their work where Michael Wright, a former curator of mechanical engineering at the Science Museum in London, had left off.

Wright built the first workable system at the front that calculated planetary motions and periods, with a coaxial pointer displaying the Cosmos, proving its mechanical feasibility – but failed at making it fully operational.

However, only about one-third of the Mechanism has survived, and it is divided into 82 fragments that have played a part in revealing a past into why the device has been difficult to decipher.

The largest fragment, known as Fragment A, shows features of bearings, pillars, and a block, while Fragment D features a disk, a 63-tooth gear, and a plate.

Researchers say the mechanism may have displayed the movement of the sun, moon, and the planets Mercury, Venus, Mars, Jupiter, and Saturn on concentric rings. Captured (bottom) are the images captured using X-ray data.

The largest fragment, known as Fragment A (a-h), shows features of bearings, pillars, and a block, while Fragment D (i-l) features a disk, a 63-tooth gear, and a plate. Images m-p are digital reconstructions of both pieces of how they originally fit 2,000 years ago.

Now that the team has an idea of how the Mechanism was constructed, the next step is to prove its feasibility by making it with ancient techniques. Pictured is the digital reconstruction of the front gear system.

Previous work used X-ray data in 2005 to uncover thousands of text characters hidden inside the fragments.

Inscriptions on the back cover include a description of the cosmos displayed, with the planets moving in rings and indicated by markers made by markers.

And this is what helped the UCL team reconstruct the device.

Two crucial numbers in the X-rays of the front cover, of 462 years and 442 years, accurately represent cycles of Venus and Saturn.

When observed from Earth, the planets’ cycles sometimes reverse their motions against the stars and the variable cycles must be tracked over a long period to accurately predict their positions.

Ph.D. candidate and UCL Antikythera Research Team member Aris Dacanalis said, “The classic astronomy of the first millennium BC originated in Babylon, but nothing in this astronomy suggested how the ancient Greeks found the highly accurate 462-year cycle for Venus and 442-year cycle for Saturn.”

Using an ancient Greek mathematical method described by the philosopher Parmenides, the UCL team not only explained how the cycles for Venus and Saturn were derived but also managed to recover the cycles of all the other planets, where the evidence was missing.

Ph.D. candidate and team member David Higgon explained: “After considerable struggle, we managed to match the evidence in Fragments A and D to a mechanism for Venus, which exactly models its 462-year planetary period, with the 63-tooth gear playing a crucial role.”

Professor Freeth added: “The team then created innovative mechanisms for all of the planets that would calculate the new advanced astronomical cycles and minimize the number of gears in the whole system so that they would fit into the tight space available.”

The Antikythera Mechanism was named after the southern Greek island where it was found, in a mid-1st century BC shipwreck, discovered first in 1901 in the Aegean Sea. The location of the shipwreck puzzled researchers.

Now that the team has an idea of how the Mechanism was constructed, the next step is to ‘prove its feasibility by making it with ancient techniques,’ added co-author Dr. Adam Wojcik (UCL Mechanical Engineering). ‘A particular challenge will be the system of nested tubed gears that carried the astronomical output.’