Archaeology & History
How Was the Nebra Sky Disk Made? A New Study Reveals Fresh Clues
A team has attempted to recreate the ancient relic.
The Nebra Sky Disk, a foot-wide metal artifact depicting the cosmos, has sparked intense debates regarding its age, origin, and meaning ever since authorities got their hands on the illegally exhumed relic 22 years ago. A new study published in Scientific Reports has set out to answer once and for all one specific question: how the disk itself was made.
Academics from Otto-von-Guericke University in Magdeburg, Germany joined forces for this research with the Saxony-Anhalt-State Museum of Prehistory, where the artifact resides, as well as local engineering firm DeltaSigma Analytics and coppersmith Herbert Bauer.
Inlaid gold shapes on the bronze disk are believed to depict a crescent moon, the full moon (or the sun), and significant stars, like the Pleiades. The horizon appears on its right, and another arc along the bottom has been said to represent either a ship or a sickle, indicating that the disk may have referenced agriculture.
Experts have analyzed the metallic makeup of the disk, determining, for example, that its copper came from the Alps and its gold inlay from Cornwall, England. Fashioning metal into a such a thin disk (it is nearly flat) was no small task for prehistoric people. Little is known about how, exactly, they made it happen.
The team behind the new study began by removing a small piece of the disk’s upper-right-hand portion to analyze its metallic makeup and microstructures. (This fleck had already been removed and reinserted shortly after the disk’s discovery.) Based on both the disk’s shape and its microscopic irregularities, detected with cutting-edge technologies like energy dispersive X-ray spectroscopy and electron backscatter diffraction, the team determined that the disk had probably been forged from a pre-made form, rather than cast from scratch.
The team recruited Bauer to simulate forging the Nebra Sky Disk himself through repeated rounds of annealing—heating a nearly identical mixture of metals up to 1,300 degrees Fahrenheit to work it, then allowing the metal to cool again to preserve its integrity before heating and working it more.
It took Bauer 55 rounds of this process to replicate the disk’s dimensions. The team used the same technologies to document the pre-form’s evolution in three stages—at one cycle, at 10 cycles, and at the end of those 55 cycles. “Surprisingly, the microstructure of the replica stage 2, instead of replica stage 3, is similar to the Nebra Sky Disk regarding all microstructural properties,” they note. “This leads to the assumption that the preform was thinner with a higher diameter than we have chosen.”
The new study’s results emphasize prehistoric people’s metalworking prowess—and prove that even the most well-researched relics still hold treasures.