The Nebra sky disk is a bronze disk of around 30 centimeters (12 in) diameter and a weight of 2.2 kilograms (4.9 lb), with a blue-green patina and inlaid with gold symbols.
Two golden arcs along the sides, marking the angle between the solstices, were added later. A final addition was another arc at the bottom surrounded with multiple strokes (of uncertain meaning, variously interpreted as a Solar Barge with numerous oars, as the Milky Way, or as a rainbow).
The disk is attributed to a site near Nebra, Saxony-Anhalt, in Germany, and associatively dated to c. 1600 BC. It has been associated with the Bronze Age Unetice culture.
The style in which the disk is executed was unlike any artistic style then known from the period, with the result that the object was initially suspected of being a forgery, but it is now widely accepted as authentic.
The Nebra sky disk features the oldest concrete depiction of the cosmos yet known from anywhere in the world. In June 2013 it was included in the UNESCO Memory of the World Register and termed “one of the most important archaeological finds of the twentieth century.”
The precise dating of the Nebra sky disk depended upon the dating of a number of Bronze Age weapons, which were offered for sale with the disk and said to be from the same site.
These axes and swords can be dated typologically to the mid 2nd millennium BC. Radiocarbon dating of a birchbark particle found on one of the swords to between 1600 and 1560 BC confirmed this estimate.
This corresponds to the date of burial, at which time the disk had likely been in existence for several generations.
Origin of the metals
According to an initial analysis of trace elements by x-ray fluorescence by E. Pernicka, then at the University of Freiberg, the copper originated at Bischofshofen in Austria, while the gold was thought to be from the Carpathian Mountains.
A more recent analysis found that the gold used in the first phase was from the river Carnon in Cornwall, United Kingdom. The tin present in the bronze was also of Cornish origin.
The Nebra sky disk as preserved was developed in four stages (Meller 2004):
- Initially, the disk had thirty-two small round gold circles, a large circular plate, and a large crescent-shaped plate attached. The circular plate is interpreted as either the Sun or the full Moon, the crescent shape as the crescent Moon (or either the Sun or the Moon undergoing eclipse), and the dots as stars, with the cluster of seven dots likely representing the Pleiades.
- At some later date, two arcs (constructed from gold of a different origin, as shown by its chemical impurities) were added at opposite edges of the disk. To make space for these arcs, one small circle was moved from the left side toward the center of the disk and two of the circles on the right were covered over, so that thirty remain visible. The two arcs span an angle of 82°, correctly indicating the angle between the positions of sunset at summer and winter solstice at the latitude of the Mittelberg (51°N). Given that the arcs relate to solar phenomena, it is likely the circular plate represents the Sun not the Moon.
- The final addition was another arc at the bottom, the “sun boat“, again made of gold from a different origin.
- By the time the disk was buried it also had thirty-nine holes punched out around its perimeter, each approximately 3 mm in diameter.
The disk may be an astronomical instrument as well as an item of religious significance. The blue-green patina of the bronze may have been an intentional part of the original artifact.
The find is regarded as reconfirming that the astronomical knowledge and abilities of the people of the European Bronze Age included close observation of the yearly course of the Sun and the angle between its rising and setting points at the summer and winter solstices.
While much older earthworks and megalithic astronomical complexes such as the Goseck circle and Stonehenge had already been used to mark the solstices, the disk is the oldest known “portable instrument” to allow such measurements. Pásztor, however, sees no evidence that the disk was a practical device for solar measurements.
Euan MacKie suggests that the Nebra disk may be linked to the solar calendar reconstructed by Alexander Thom from his analysis of standing stone alignments in Britain.
*This article was originally published at en.wikipedia.org.