Secrets of the Star Disc - questions and answers
Why was Northern Europe thought of as unsophisticated in the Bronze Age?
In pre-history, the most advanced societies include the Egyptians, Minoans and the Babylonians. Much later the Greeks and then the Romans came to prominence. These societies all emerged in what’s considered as one of the cradles of civilisation, the Eastern Mediterranean. Evidence for the sophistication of these societies is abundant – great architecture survives, astronomical depictions exist, writing was created, forms of mathematics developed. And vitally, this knowledge was preserved – written down on scrolls or carved into walls of buildings.
The Bronze Age in north and central Europe is much more mysterious. While a great deal of archaeological evidence survives, it speaks of a much more primitive society – domestic debris, tools, jewels and weapons. What this tells archaeologists is that the people who lived then knew how to hunt, lived in small settlements and were ruled by the sword. What doesn’t survive is writing or even pictures, the type of information that would allow archaeologists to understand much more about the people of the European Bronze Age and their beliefs. By the end of the Bronze Age – around 1000BC, ideas such as bronze making, the wheel, armour-making technology had clearly spread across Europe. But art and writing does not appear until much later, and the period still remains literally at the margins of history, barely visible through the mists of time.
How can corrosion be used to demonstrate the authenticity of an archaeological find?
Corrosion has a personality. It forms in crystals and over time these crystals grow and grow. Eventually they become very large and cover the entire the object. These corrosion crystals are green and eventually, the entire bronze object would be green and coated in a shiny patina of corrosion. The size of these crystals of corrosion is the key to determining how long they have been forming. It would take thousands of years for the large crystals of corrosion on the Nebra Star disc to form.
How can corrosion be faked?
Corrosion can be faked either chemically or by electro-chemical means. The crudest and most simple way is to simply pass a small electric current through a piece of bronze. After just 24 hours, corrosion would be noticeable.
What is carbon dating?
Carbon dating is one of the most powerful tools archaeologists possess for dating ancient objects. Anything that has lived and breathed – all plants and animals - contains small traces of radioactive Carbon 14. These traces, because they are radioactive and possess a radioactive half life, can be measured back through time and the precise age of the carbon-containing fragments can therefore be fixed. Metal does not contain carbon and therefore cannot be carbon-dated. But metal can lie in the soil at the same level as small particles of charcoal or skin or wood – and these tiny scraps of seemingly unimportant debris can become vital for dating much more important finds.
What is associative dating?
Associative dating is when an archaeological find is dated through comparison with other objects whose age and origin are well established. The swords on the Nebra disc bear a striking similarity to swords found in central Europe. These swords were themselves securely carbon-dated to 1600 BC.
How had the swords that were used for the associative dating been dated?
The swords were matched by Harald Meller against pictures of swords in his museum in Halle. Most archaeologists possess expert knowledge of the fine details of the important objects in their field. Any new archaeological find - if it is part of a common group of objects, such as swords or spear heads or pots, for instance – can be matched with those already known whose age has been established by carbon dating. In the case of the disc, it could not be dated by association because nothing like the disc had ever been seen before. There was literally nothing to compare it with.
How did the scientists know what the disc was found with?
The disc was offered for sale with the swords and jewels from the outset. When all of the artefacts had been recovered and brought back to the museum, soil analysis proved scientifically that the disc and the swords had been found together.
What are lead isotopes and how were they be used to discover where the disc was made?
Bronze is made of copper and tin. And copper contains traces of impurities such as uranium. When these impurities decay, radioactive lead particles are formed. And the abundance of these lead isotopes can be measured – they give each sample of copper ore a fingerprint. The impurities vary from place to place around the world – one sample might contain very few lead isotopes, another sample might contain many. The 'lead isotope fingerprint' of copper from the major European and Mediterranean sources can therefore be measured and any new object can be compared with these.
Are archaeologists expecting to find more evidence that people in Northern Europe were more sophisticated in the Bronze Age than previously thought?
The bronze age in Europe will always be mysterious compared with the classical civilisations around the Mediterranean. But an object like the Nebra star disc allows archaeologists to understand that the people in northern and central Europe must have had contact with ideas from across the known world and that inevitably, they must have been more sophisticated than once thought.