The Antikythera Mechanism, circa 205 BCE, Bronze
Fragment A above: 140 millimetres (5.5 in) [diameter]
The National Archaeological Museum of Athens, Greece
So what did the Antikythera Mechanism do? Well, scientists and historians are still working on uncovering the finer parts of the mechanism: but, thanks to the fact that we can now use X-ray analysis to read parts of the inscriptions that cover the machine, we are beginning to get a clearer picture. It seems that it was used as a sort of portable astronomical calculator – probably both for scientific calculations as well as for teaching purposes. It displayed the positions of the Sun, the Moon and (probably) the five planets known in antiquity, Mercury, Venus, Mars, Jupiter and Saturn; it could be used to predict solar and lunar eclipses, and displayed the dates of Pan-Hellenic games (from which dates in the ancient world were calculated before the birth of Christ). It was originally dated to the 1st century BCE, but that dating has since been challenged and an earlier date of 205 BCE suggested.