German researchers have reconstructed the ancient manufacturing process of the Nebra Sky Disc, one of Europe’s best-known archaeological finds, and discovered the impressive metallurgical skills of Early Bronze Age craftsmen.

The 3,600-year-old Nebra Sky Disk. Credit: Frank Vincentz

Discovered in 1999 on Mittelberg Hill near Nebra, Germany, the Nebra Sky Disc is a 30-centimeter-diameter bronze artifact. The disc holds gold inlays that represent celestial elements: the full moon or sun, crescent moon, and stars. The disc dates to between 1800 and 1600 BCE and is ᴀssociated with the Únětice culture. It is, in general, regarded as the oldest representation of the cosmos in the world.

Researchers at Otto von Guericke University Magdeburg, in collaboration with the State Office for Heritage Management and Archaeology of Saxony-Anhalt, employed modern forensic analysis and experimental archaeology to uncover the process of producing the disc. The team, led by Professor Dr. Thorsten Halle from the Insтιтute for Materials, Technologies, and Mechanics, used scanning electron microscopy and electron backscatter diffraction to analyze a very tiny sample of the original disc. These techniques helped them analyze the crystal structure of the metal and understand the heating and working processes the disc underwent.

According to Halle, the disc was initially cast at over 1200°C, with subsequent repeated heating to around 700°C and forging approximately ten times. This cycle of heating and reshaping is typical of a process known today as recrystallization, in which the metal “heals” by forming new grains following deformation, restoring its softness and workability.

Dr. Christian-Heinrich Wunderlich from the State Office for Monument Preservation and Archaeology of Saxony-Anhalt (front) with a replica of the Nebra Sky Disc, and Prof. Dr. Thorsten Halle from the Insтιтute for Materials, Technologies, and Mechanics at Otto von Guericke University Magdeburg (back), in the laboratory on the university campus where the investigations took place. Credit: Jana Dünnhaupt/University of Magdeburg

“This kind of detailed manufacturing process is remarkably similar to modern industrial procedures,” Halle explained. “We’re conducting metallurgical forensics—reading the metal’s history like a diary.”

The researchers found that the final stage of crafting, particularly the thinning of the disc’s edge, was done cold—a detail that reflects an advanced, experience-based understanding of metal behavior, despite the absence of written knowledge, machines, or measuring tools.

To experiment with the production process, the team collaborated with master coppersmith Herbert Bauer to produce multiple replicas of the disc using Bronze Age equipment and techniques, such as stone hammers and charcoal hearths. The replicas were inspected under the same conditions as the original and compared with it. Microstructure similarities confirmed the presumed production process.

Their research was published in November 2024 in Nature Scientific Reports and received global attention. The study not only sheds light on ancient craftsmanship but also hints at the greater potential of materials science.

Now, researchers in Magdeburg are developing a mobile app based on eddy current technology that will allow archaeologists to analyze the material history of metal artifacts in the field with a smartphone, without damaging the object.