Every now and then one comes across an item of real beauty which stops you in your tracks. It was a great pleasure to the Nebra Sky Disk to my list recently. The replica of the Nebra Sky Disk appeared in the National Museum Museum Cornwall in 2012 to accompany our Bronze Age boat exhibit. In 2022, the original featured in the Stonehenge exhibition at the British Museum. The interest in this amazing object is both intellectual as aesthetic: solving the puzzle of its history for it is probably the earliest depiction of the heavens so far found.
One of the great joys of the Bronze Age is that there is plenty of space for the amateur to speculate, safe in the knowledge that no one is going to say definitively that one is right or wrong. And it is to the Middle Bronze Age that we must turn: some time after 1600 BC, somewhere in the wilds of what was once Eastern Germany, on the 252 metres (827 ft) high Mittelberg hill just outside a small village called Nebra 60km to the west of Leipzig. In some sort of ceremony a collection of two bronze swords, two small axes, a chisel and fragments of spiral bracelets were placed on the ground in front of a 32cm disk of copper covered with gold decorations which was carefully propped up against some stones. The hoard was covered over and forgotten for a few thousand years.
Skip forward to 1999 and two men with metal detectors got a signal from their machines and attacked the ground with a pick axe. Eventually they retrieved the hoard and spirited it away to try and sell in the illegal art market. Apparently metal detectors were the new toy to have in post-Communist East Germany and the countryside was being swept by people keen to turn a dishonest Euro by selling artefacts into the art trade, depriving archaeology of important information.
What followed was the stuff of a detective story with police and museums picking up rumours of a spectacular find; of the objects changing hands for ever increasing values; and of the police eventually picking up a lead. At a dramatic meeting in the Hilton Hotel in Basel, Switzerland, the police arrested and charged two people and the hoard was recovered. The finders cooperated with archaeologists before spending time in prison and the site of the find was extensively excavated.
The discovery site turned out to be in the middle of a prehistoric enclosure hidden away in what is now the Ziegelroda Forest but must once have been an open space. The area would have been on a north-south trade route with amber, copper, tin and gold thought to have been traded in this area in the Middle Bronze Age. Within sight of the hill were two 'magical' hills and a variety of henge monuments have been found in the wider area.
The treasure-hunters damaged the disc with their pickaxes when they removed it from the ground, denting the top left hand side and tearing off part of the ‘sun’ disc. They then tried to clean it, scratching the surface. The left hand arc was never found and the thought is that this must have come unstuck in ancient times. A small piece in wood found in one of the swords allowed scientists to date the hoard to around 1600 BC.
This is where the fun begins for now archaeologists and scientists had to try and work out what this strange object was, what it meant and how it might have been used. They quickly identified five stages for its creation shown by the way in which the symbols were arranged and the composition of the metals. What follows is the generally accepted view of its history. What it depicts and its purpose are the subject of wider speculation.
Stage 1: an indicator of the equinoxes?
The first stage seem to have been an indicator of the spring and autumn equinoxes which would have been useful for judging the best times for sowing and harvesting crops. As one German scientist remarked 'the winters are pretty grey and overcast in that part and it would be difficult to judge the time of year accurately'. It sounds a great tourist destination.
When originally constructed the disc consisted of the bronze disc with what look like a crescent moon, a full moon (or is it a sun?), and 32 stars, inlaid in gold. The cluster of seven stars is interpreted as being the Pleiades, a very obvious group of stars in the night sky which are a familiar sight in the northern hemisphere in winter. They disappear from view around 10 March and appear again around 17 October, close to the equinoxes which were important times for sowing and harvesting crops.
The general consensus is that the round object is actually the full moon. If the Pleiades were associated with a full moon in the Spring then they would be associated with a crescent moon in October. I have certain problems with this idea since I would have thought they would have experienced all phases of the moon during the six months they were visible but I need to find a good astronomer to explain this to me.
In an era when survival depended on agriculture, as it had done for the 5,000 years since agriculture had been invented, knowledge of the seasons must have been essential. As the nights became longer into the cold of winter - and particularly the bitter cold of a continental winter - it must have been a constant worry that the year would descend into total darkness and consequent starvation. The turn of the year when the days actually started getting longer again must have been a vitally important time, only matched by the knowledge that seeds could be planted to be followed by the green shoots of the crop.
Any signal that helped mark the warming of the ground with spring, even through the murk of a northern winter, would have been a welcome sign. Shamans would have had an important role to play in ensuring that the natural cycles happened and that they were celebrated whether by divination or appeasement of the gods or ancestors in and around significant tombs. The sky disk could help to determine this point: the spring and autumn equinoxes.
That is the easy bit: the Pleiades are the companions of winter. When they have gone we can begin to look forward to warming days and summer. When they appear then it is time to batten down the hatches for winter.
The relative position of the Pleiades and the two moons might have been used to help identify these dates. But what of the 32 stars? Why this number and so they represent some other constellation or event. Astronomers compared the layout with the night sky and could find no connection although some argue that there is an alternative interpretation to which I return later.
The currently accepted belief is that the 32 stars allow for the insertion of a leap month which is needed every three years. The astronomy is complicated but suffice it to say that 365 days is not a whole multiple of the 29.5 days of the lunar cycle. The moon lags the sun by roughly 11 days a year (12 x 29.5 = 354). Sailors and fishermen know this because the spring tides appear in roughly alternate weeks each year. The theory is that to stay in step you need a leap month every three years but at this point I lose the plot as 3 x 11 is not 29.5 nor 32 but the astronomers have an answer to this which I have yet to understand. Suffice it to say, that the 32 stars could have been a way of calculating this leap month, reassuring the shaman that the Pleiades were in the 'correct' place in relation to the new or crescent moon. If so, then it was clearly a very sophisticated piece of equipment.
Stage 2: indicator of the solstices?
The next development went further. Knowing the equinoxes was one thing but what about midwinter and midsummer? The henge monuments would have indicated this with their equivalent of Stonehenge's heel stones aligned on the relevant sunrises and sunsets.
To add the bands meant that four stars had to be covered up. One was moved a short distance. The archaeologists suggest that this shows that the disc's use as a calculator of leap months was then lost, possibly because it no longer worked or because the shamans had lost an understanding of the system.
An off-the-wall suggestion is that it was not the knowledge that was lost but the sun. We do not know exactly when the great eruption of Thira (Santorini) took place but it is generally believed to have affected the climate. If the sun, moon and stars were blotted out by years of cloud, or the morning and evening skies were filled with dust, preventing an accurate sighting of the place of rising and setting, then the disc would rapidly have lost its utility. Pity the poor shaman of the time.
The bands divided the year into four: the seasons. But here again, I have a problem. The disc would only work effectively if it were fixed to the ground and yet there are no signs of fixing and no signs of any alignment points such as notches.It would have been little use as a portable measuring device without some way of orientating it. Where is the mark showing where north or south are so that the whole could be aligned?
South is relatively easy to find on any day: it is either in the direction of the sun at its highest point - not very easy to measure - or half way between the sunrise and sunset. All you needed was a good sunrise and sunset, bisect the angle and there was south. Point the sky disk towards south and the position of the sunrise or set would give you an indication of how far the year you were like a giant portable sundial. Without a mark for south on the disk, this was not an option.
An intriguing idea, however, is that it could be used as an architect's plan for a henge. Imagine you were building your henge and needed to know where to put the entrances so that they aligned on the relevant sunrises and sunsets. You could wait a whole year, putting sticks in the ground to mark the movement various positions but it would have been much easier to call in the sky disk shaman. He could have told you exactly here to put the entrances, using the bands. Sadly, this would not have been terribly accurate, however.
The 82-83°angle between the midwinter and midsummer sunrises - or midwinter and midsummer sunsets - shown by the bands is very significant. This angle would only apply in a relatively narrow band of locations across Northern Europe, on a latitude which includes modern places like Bristol, London, Amsterdam or Warsaw. Nebra is close to this zone. This suggests that it was manufactured for use in these latitudes, ruling out the idea that it might have been produced by a 'more sophisticated' society in or around the Mediterranean. Mycenae, for example, was at its height at this time.
Stage 3: ritual object?
The next stage of the disc's life may well have been as a ritual object of some form. A third band was added at the bottom.
This device is very unusual and archaeologists think it might represent a boat, especially because of the little marks on the side which might represent oars. It was certainly added by a slightly different technique and carefully avoided any of the stars.
The image of a boat was often used with one of a sun in the Bronze Age on artefacts from as far afield as Scandinavia and Mesopotamia. The Egyptian sun god, Ra, is often depicted on a boat. This has led to the suggestion that people in this period believed that, once the sun had set in the evening, it was given safe passage through the night on a boat, to rise again the next morning.
Again, this sets the mind racing. If you lived in the middle of Northern Europe then how could you imagine the sun travelling on a boat? The natural place to invent such a myth would be on an island where the sun could be seen rising out of the sea in the morning and setting into it in the evening. If the sun went into the sea at night and reappeared out of it in the morning then the only way in which it could have got from one place to the other without sinking, would have been by boat. But in Northern Europe it would have disappeared behind a hill and reappeared from behind another one. How could one imagine a boat as being useful? The myth could of course have travelled but I would not have wished to have explained it to a bright Bronze Age child.
Stage 4: simple decoration?
The last stage of the sky discs use was probably as a simple decoration. About 38 or 40 small holes were punched around the outside of the disc, damaging parts of the decoration. The craftsmanship was lower suggesting it was of less importance. Perhaps this was done to attach it to something: a piece of cloth, a tunic or a post. The damage suggests that the disc was losing its power: it was not seen as being as important for calculation as it had been formerly. Or maybe they had finally realised it needed to be fixed to the ground to work effectively.
And then there was the burial. It was buried in the ground, standing upright with the ‘boat’, or south, at the bottom of the disc, and with its back resting against a stone. The other items of the hoard were laid out around it. No body or signs of a body were found close by. This was not a casual act or done in a hurry when invading tribes threatened. This suggests a deliberate and careful burial, perhaps with an associated ceremony.
What helps to make the disc so significant is that the image of the Pleiades and sun boats predate those from Babylon and Egypt, making it the earliest such depiction yet found. Up until now, archaeologists thought that detailed understanding of the stars and astronomy had started in the Middle East and that the Bronze Age society of Northern Europe was relatively primitive. The discovery of the disc turns this belief on its head and suggests that sophisticated knowledge of the stars was available in Northern Europe much earlier than previously thought.
An alternative explanation?
I said at the beginning that the joy of the Bronze Age is that we are all allowed our own interpretations. Someone called Anders Kaulins has written perhaps the most complete alternative explanation. He agrees with much of the 'conventional' story set out above but argues that Stage 1 of the disk actually shows the solar eclipse of 16 April 1699 BC. This happened to take place near the Pleiades at the same time as Mercury, Mars and Venus were nearly in conjunction. The large object is indeed the sun. These planets, in his interpretation, are the three dots by the crescent moon. The dots to the left of the 'sun' are an interpretation of Ursa Major, the familiar shape of the great bear. Other constellations included are Lupus, Eridanus and Capricorn.
The choice of constellations in this interpretation seems haphazard. On 16 April Aries should dominate and yet is not mentioned. And why would anyone miss out the very recognisable and bright stars of Orion, or the Pole star which even a Bronze Age shaman should have worked out was the one star that appeared never to move in the heavens?
How was it made?
The sky disc is a fine object requiring many hours’ work to create. From a rough-cast flan of soft bronze, the maker beat out the disc until it was c. 32 cm in diameter. This would have been no easy task.
Bronze is an alloy of copper with a small amount of tin. Extensive research of the trace elements in the bronze has suggested that the copper came from an ancient mine near Salzburg in Austria about 350 miles away from the find site.
The tin is a different story. Research suggests that the tin actually came from Cornwall. We can be even more precise about the gold for stage 1: this came from somewhere near Carnon or Feock on Restronguet Creek, possibly washed down from the Poldice valley.
Manufacture of the disc in, or near, Central Europe seems likely. The heavier part, the copper, coming from Austria and the two minority metals, the tin and the gold, being traded all the way from Cornwall. Naturally, those of us living in Cornwall, prefer to think that it might have been manufactured here.
To unite three minerals from so far apart implies trading routes and, at some point, the goods would have had to cross the sea to reach mainland Europe. The discovery of the remains of a Bronze Age cargo off Salcombe is evidence that coasting transport was in use.
Knowledge follows trade routes. The sophisticated knowledge of the makers of the sky disc might well have filtered back to Cornwall. We cannot know. All we can do is stand on a high spot in Penwith, surrounded by the remnants of the Bronze Age, look out towards the sea and dream, wondering at the skill of those craftsmen nearly four thousand years ago, trying to understand what they were trying to tell us.
See also: Wikipedia, the Kaulins explanation,
