After Greek sponge divers stumbled on the wreck of an ancient ship off the coast of the island of Antikythera in 1901, excavations recovered a massive haul of treasures including glassware, ceramics, furniture, jewelry and statues of both marble and bronze. By far the most stunning artifact recovered, however, was a mangled, fragmented jumble of bronze gears and plates, all encrusted with centuries’ worth of sediment.

Dating to the first century B.C., the so-called Antikythera mechanism stands as one of the most exciting archaeological discoveries ever made. It has been called the world’s first mechanical computer, showcasing the engineering prowess of the ancient Greeks as well as their impressive knowledge of astronomy. Nothing else like it would emerge for more than 1,000 years.

Though the physical workings of the gears and other parts of the multi-layered mechanism are well understood, scientists have long been puzzled by the thousands of characters engraved on the inside covers and front and back sections. They suspected the text might contain some kind of operating instructions or user’s manual for the device, but with some of the letters measuring just 1.2 millimeters (or 1/20 of an inch) tall, the text was impossible for them to decipher.

The Antikythera Mechanism known as the world’s oldest computer. (Credit: LOUISA GOULIAMAKI/AFP/Getty Images)

But after more than a decade using X-ray scanning and other cutting-edge techniques, an international team of researchers has been able to decipher about 3,500 characters of the explanatory text carved on the Antikythera mechanism. It was painstaking work, as the researchers were forced to examine dozens of scans in order to read each tiny letter. They announced their findings in an event held at the Katerina Laskaridis Historical Foundation Library in Athens.

“Now we have texts that you can actually read as ancient Greek, [while] what we had before was like something on the radio with a lot of static,” Alexander Jones, a professor of the history of ancient science at New York University, said at the event. “It’s a lot of detail for us because it comes from a period from which we know very little about Greek astronomy and essentially nothing about the technology, except what we gather from here.”

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What Jones and his colleagues discovered in their analysis confirms much of what we already know about the Antikythera mechanism, but adds some intriguing new insights. In addition to serving as a solar and lunar calendar, showing phases of the moon as well as the position of the sun, moon and planets in the zodiac, it appears that the device was also able to predict the color of a future eclipse.

According to Mike Edmunds, a professor of astrophysics from the University of Cardiff in Wales who is also part of the research team: “We are not quite sure how to interpret this, to be fair, but it could hark back to suggestions that the color of an eclipse was some sort of omen or signal. Certain colors might be better for what’s coming than other colors.”

Rather than an instructional manual, the researchers said, the text engraved on the Antikythera mechanism was more like a long label used to describe a display at a museum. Edmunds explained that the formal, detailed quality of the text indicates that the mechanism wasn’t just the trinket of a wealthy Greek collector, but was clearly something “more serious than a toy.”

The Antikythera Mechanism. (Credit: LOUISA GOULIAMAKI/AFP/Getty Images)

The researchers believe that in addition to astronomers and astrologers, ancient philosophers would have made use of the device to better understand the galaxy and the place of humans in it. According to Jones: “It’s like a textbook of astronomy as it was understood then, which connected the movements of the sky and the planets with the lives of the ancient Greeks and their environment.”

Though no maker’s signature has been found on the Antikythera mechanism, the researchers found that the device was probably made on the Greek island of Rhodes.

They also don’t think it was the only one of its kind made, though no others have been found to date. Slight variations in the inscriptions suggest that at least two people worked to construct the device, and the researchers think it came from a small workshop, rather than an individual craftsman.

Researchers have been able to decipher most of the characters on the mechanism’s 82 surviving fragments, which is believed to be a quarter of the original text. They’re still holding out hope that future excavations of the Antikythera shipwreck will be able to recover the remaining inscriptions, which are presumably still resting at the bottom of the sea along with at least 20 additional gears used to power this remarkable ancient machine.

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