The Antikythera Mechanism is the earliest known device to contain an intricate set of gear wheels. It was retrieved from a shipwreck off the Greek island of Antikythera in 1901 but until now what it was used for has been a mystery.
Although the remains are fragmented in 82 brass pieces, scientists from Britain, Greece and the United States have reconstructed a model of it using high-resolution X-ray tomography.
They believe their findings could force a rethink of the technological potential of the ancient Greeks.
"It could be described as the first known calculator," said Professor Mike Edmunds, a professor of astrophysics at Cardiff University in Wales.
Scholar says there is nothing like it in the history of astronomy