Could a 3,000-Year-Old Stone Disk Be the Earliest Star Map?

In northeastern Italy, researchers uncovered a stone disk marked with chisel traces that may be a star map. Researchers from Ca’ Foscari University of Venice (UNIVE) and the Italian National Institute for Astrophysics (INAF) say the ancient tool could have helped people time agricultural activities.

The 50-centimeter stone disk was found at the ancient settlement of Castelliere di Rupipicolo in the province of Trieste. Archaeologist Federico Bernardini and astronomer Paolo Molaro said the disk intrigued the team because of 29 mysterious chisel marks. Twenty-four marks sit on one face of the stone, and five are on the opposite side. Near the possible star map they found another unworked stone of the same diameter that might represent the Sun.

What the Team Discovered

Using software to analyze the carvings, the team found the markings likely correspond to star groups in the constellations Orion, Scorpius, and Cassiopeia, and to the Pleiades cluster.

A paper in the journal Astronomical Notes says one of the 29 markings remains unidentified.

The team suspects the unknown mark is probably a star in Orion. It might have exploded as a supernova—or been the remnant of a failed supernova that left behind a black hole.

“The unknown mark challenges the entire picture. We believe it could be the remnant of a failed supernova,” the authors wrote. They suggested that searching for a black hole in that patch of sky could confirm the idea, the Independent reported.

The team also proposed the disk may have been used by people at the settlement around 3,000 years ago as a calendar for agricultural work.

Pottery fragments found nearby indicate the hillfort was in use from roughly 1800–1650 B.C. up until about 400 B.C., putting the stone disks somewhere in that broad span. Little is known about the ancient inhabitants of Castelliere di Rupipicolo, however.

Until now, the oldest known star map was attributed to Greek astronomer Hipparchus, around 135 B.C.

The Nebra sky disk, a bronze artifact with gold appliqués marking the Sun, Moon, and Pleiades, is dated to about 1600 B.C., making it older. But researchers consider its images fairly primitive.

If proven a map of the sky, the stone disk could be one of the oldest known artifacts of its kind.