The Antikythera Mechanism

When researchers finally analyzed the object using X-rays and CT scans, they discovered something that shouldn't have existed: a complex mechanical computer built more than two thousand years ago.

The Antikythera mechanism dates to approximately 100 BCE. About the size of a shoebox, it originally contained at least 37 interlocking bronze gears arranged to calculate astronomical phenomena with remarkable precision. Nothing remotely comparable would be built in Europe for another thousand years, until medieval clockmakers began constructing cathedral clocks in the 14th century.

The device tracked the movements of the sun and moon through the zodiac, predicted solar and lunar eclipses decades in advance, and modeled the irregular orbit of the moon—a calculation that requires compensating for the elliptical shape of its path around Earth. A subsidiary dial tracked the four-year cycle of the Panhellenic games, including the Olympics at Olympia, the Pythian games at Delphi, and the Isthmian games at Corinth. Another dial showed the rising and setting of specific constellations.

The mechanism was likely connected to the island of Rhodes, which was a center for astronomy in the 1st century BCE. The astronomer Hipparchus, who worked on Rhodes and developed sophisticated theories of celestial motion, may have been involved in its conception. Researchers have described the device as "almost unbelievable in its brilliance."

The ship carrying the mechanism sank sometime in the early 1st century BCE, likely while transporting luxury goods from the eastern Mediterranean toward Rome. The computer spent the next two thousand years on the seafloor, its gears frozen by corrosion. What other devices like it may have existed in the ancient world remains unknown.