Stages of production

The studies of the materials show that the Sky Disc had been altered a number of times before it was deposited around 1600 BC. In its first version, it showed only the larger heavenly bodies and the stars. The barque and the horizon arcs are not present.

X-ray images show that two more stars are hidden below the arc on the left, and a star on the left-hand side was moved to make way for the arc. The different style of work in the inlay grooves of the ‘sun’ and of the arcs, respectively, suggest that the alteration was made by a different smith, perhaps after a considerable period of time. A groove in the back of the disc, undercutting the surface deeply, is probably the work of the second craftsman. It is formed like an inlay groove and is most likely the result of a trial run, to try out the tool and technique on the unfamiliar material.

The celestial barque was added in a third, even later stage. It does not fit harmoniously into the starry sky and looks ‘squashed in’. The fringes marked on the barque anxiously work around one star: in contrast to his predecessor, this smith has decided not to move the star to a new position.

The chemical analysis of the gold objects, carried out by the Berlin electron storage ring (BESSY) using synchrotronic x-ray fluorescence, confirms the hypothesis of three stages of work. Each set of objects belonging to a single phase is made from a different batch of gold. When the star next to the left-hand arc had to be moved, its gold plate was not re-used; plate from the new batch of gold was used instead.

In the course of a subsequent change in use, the disc was perforated around the edge. The holes are made with a typical technique using a bronze hole-punch (‘drift punch’), but with very little concern for the imagery, and elements that must once have been important, such as the barque, have been damaged. It is not possible to establish for certain what the holes were for. One possibility is that the disc was to be riveted to a mildly flexible support, for example onto a thin wooden board (a shield?), or onto leather or textile.

Pictures taken soon after the Sky Disc was found show that the left-hand arc did not get lost when the object was unearthed, but must have already have been missing when the disc was deposited around 1600 BC. There are many possible explanations for this: either this arc was made from a perishable material, or perhaps it was intentionally removed, or came off when the rivets with which the disc was attached were extracted.