Archaeology breakthrough into 3,600 year old ‘sky disc’

Archaeologists may have solved one of the mysteries surrounding an enigmatic artefact that is more than 3,600 years old.

The Nebra Sky Disc is believed to be the oldest precise depiction of the heavens in human history.

This beautiful Bronze Age object is believed to have been used to observe and track astronomical phenomena, such as solstices.

Made from copper, tin and gold mined from across Europe, it is attributed to the central European Únětice culture – and it is believed to have been created in at least four stages, as new astronomical observations were added. However, scientists have long been puzzled about the precise manufacturing process that was involved.

Now, using cutting-edge new methods, modern scientists have discovered that the ancient cultures of the Bronze Age had a far greater level of metalworking expertise than was previously realized.

The disc was discovered in 1999 by illegal treasure hunters using metal detectors near the town of Nebra in Germany. It was part of a buried horde that included two swords, two axes, a chisel, and fragments of bracelets.

Instead of declaring their find, which is which is a legal requirement in Germany, they sold their haul on the black market. The disc changed hands multiple times, often at inflated prices, before it was seized in a police sting operation in 2002.

Its authenticity was initially questioned due to its extraordinary nature, but thorough analyses confirmed it was a genuine artefact from the Bronze Age.  Despite being found in Germany and associated with central European cultures, chemical analysis shows that some of the metals used in its earliest construction came from Cornwall – and others came from Austria.

Now housed in the State Museum of Prehistory in Halle, Germany, it is recognised as being one of the most significant archaeological finds of the 20th century. It has fueled debates about early European societies’ astronomical knowledge and cultural sophistication.

A new study will fuel that discussion even further – as it shows Bronze Age craftsmen had a greater level of expertise than had been previously acknowledged. The latest metallographic research, published in Nature’s Scientific Reports, shows that it was manufactured from a flat cast, followed by a hot forging process – which saw the disc heated to around 700c and forged approximately ten times.

The paper’s authors write: “The Nebra Sky Disc is an extraordinary relic of the Early Bronze Age and an impressive example of the profound knowledge that was available in the Únětice culture. Since it proves a detailed understanding of astronomic correlations, it became a UNESCO Memory of the World.

“Furthermore, its manufacture was by no means trivial. While the production of axes and sheet metal jewellery by forging techniques were common practice in the Central European Early Bronze Age, the Nebra Sky Disc is, according to current knowledge, unique in its shape, size and volume.

“The influence of the Únětice culture on Early Bronze Age metallurgy has been often discussed, with a particular focus on innovative casting techniques. In this context, the Nebra Sky Disc documents, that the Únětice culture craftsmen were excellent and innovative copper smiths with extensive experience in sophisticated bronze manufacturing, including casting, forging and heat treatment.”

Dr Harald Meller, a state archaeologist professor, said the new discoveries show how important it is that well-known finds are re-examined when new scientific methods become available.

He added: “That the investigations continue to produce such fundamental new findings more than 20 years after the Sky Disc was secured not only once again demonstrates the extraordinary character of this find of the century, but also how highly developed the art of metal processing was already in the Early Bronze Age.”

The research was conducted by the State Office for Heritage Management and Archaeology Saxony-Anhalt in cooperation with the Otto von Guericke University Magdeburg, chair of metallic materials (Prof. Dr. Thorsten Halle), and the company DeltaSigma Analytics GmbH, Magdeburg.