The Nebra Sky Disk

Explanation: Some consider it the oldest known illustration of the night sky. But what, exactly, does it depict, and why was it made? The Nebra sky disk was found with a metal detector in 1999 by treasure hunters near Nebra , Germany , in the midst of several bronze-age weapons . The ancient artifact spans about 30 centimeters and has been associated with the Unetice culture that inhabited part of Europe around 1600 BC . Reconstructed, the dots are thought to represent stars , with the cluster representing the Pleiades , and the large circle and the crescent representing the Sun and Moon . The purpose of the disk remains unknown -- hypotheses including an astronomical clock , a work of art, and a religious symbol. Valued at about $11 million , some believe that the Nebra sky disk is only one of a pair, with the other disk still out there waiting to be discovered.