This is pretty cool. The famous Antikythera Mechanism has been rebuilt to scale, and it works perfectly. So what did this ancient machine do?

“In short, Antikythera’s user interface is deceptively simple, operated by a simple knob on the side. This conceals the intricacy within, amounting to a complex mathematical model, tracking the movements of planetary bodies and incorporating a series of submechanisms to account for the eccentricities of their rotation.”

And for all those out there that will want to attribute this early computing machine to extraterrestrials, take note that the machine only accounts for five planets — since only five were known in antiquity. If ET knew only five planets, he’s a pretty incompetent astronomer for being so “advanced.”