Nebra sky disc



The Nebra sky disc (Himmelsscheibe von Nebra, ) is a bronze disc of around 30 cm diameter and a weight of 2.2 kg, having a blue-green patina and inlaid with gold symbols. These symbols are interpreted generally as the Sun or full moon, a lunar crescent, and stars (including a cluster of seven stars, axiomatically interpreted as the Pleiades ).

Two golden arcs that were along the sides are thought to mark the angle between the solstices, one now is missing. Another arc at the bottom with internal parallel lines is usually interpreted as a solar boat with numerous oars, although some authors have also suggested that it may represent a rainbow, the Aurora Borealis, a comet, or a sickle.

The disc was found buried on the Mittelberg hill near Nebra in Germany. It is dated by archaeologists to c. 1800–1600 BC and attributed to the Early Bronze Age Unetice culture. Various scientific analyses of the disc, the items found with the disc, and the find spot have confirmed the Early Bronze Age dating.

The Nebra sky disc features the oldest concrete depiction of astronomical phenomena 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."

Discovery
The disc, together with two bronze swords, two sets of remains of axes, a chisel, and fragments of spiral armbands were discovered in 1999 by Henry Westphal and Mario Renner while they were treasure-hunting with a metal detector. The detectorists were operating without a license and knew their activity constituted looting and was illegal. Archaeological artefacts are the property of the state in Saxony-Anhalt. They damaged the disc with their spade and destroyed parts of the site. The next day, Westphal and Renner sold the entire hoard for 31,000 DM to a dealer in Cologne. The hoard changed hands, probably several times, within Germany during the next two years, being sold for up to a million DM. By 2001 knowledge of its existence had become public.

In February 2002, the state archaeologist, Harald Meller, acquired the disc in a police-led sting operation in Basel from a couple who had put it on the black market for 700,000 DM. The original finders were eventually traced. In a plea bargain, they led police and archaeologists to the discovery site. Archaeologists opened a dig at the site and uncovered evidence that supported the looters' claims. There were traces of bronze artefacts in the ground, and the soil at the site matched soil samples found clinging to the artefacts. The disc and its accompanying finds are held by the State Museum of Prehistory in Halle, Saxony-Anhalt, Germany.

The two looters received sentences of four months and ten months, respectively, from a Naumburg court in September 2003. They appealed, but the Appeals Court raised their sentences to six and twelve months, respectively.

The discovery site is a prehistoric enclosure encircling the top of a 252 m elevation in the Ziegelroda Forest, known as Mittelberg ("central hill"), some 60 km west of Leipzig. The surrounding area is known to have been settled in the Neolithic era, and Ziegelroda Forest contains approximately 1,000 barrows.

At the enclosure's location, the sun seems to set every summer solstice behind the Brocken, the highest peak of the Harz mountains, some 80 km to the northwest. The treasure hunters claimed the artefacts were discovered within a pit inside the bank-and-ditch enclosure.

Dating
Axes and swords found buried with the disc were dated typologically to c. 1700–1500 BCE. Remains of birch bark found in the sword hilts have been Radiocarbon dated to between 1600 and 1560 BCE, confirming this estimate. This corresponds to the date of burial, at which time the disc had likely been in existence for several generations. Analyses of metal radioactivity and the corrosion layer on the disc further support the early Bronze Age dating.

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, whilst the gold was thought to be from the Carpathian Mountains. A more recent analysis found that the gold used in the first development phase (see below) was from the River Carnon in southern Cornwall in England. The tin present in the bronze was also of Cornish origin.

History
As preserved, the disc was developed in four stages:
 * 1) Initially the disc 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 a star cluster. The star cluster is thought to refer to the Pleiades, or possibly the general symbol of a star cluster.
 * 2) 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 disc. To make space for these arcs, one small circle was moved from the left side toward the centre of the disc 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 sunsets at summer and winter solstice at the latitude of the Mittelberg (51°N).  The arcs relate to the Sun's path – the ecliptic. Given that ancient astronomers knew the planets and many stars that mark the ecliptic, they could observe it sweep across the horizon within the arcs, in a single winter night, not just sunrise and sunset over an entire year. Thus, the arcs are consistent with wholly nighttime use.
 * 3) The final addition was another arc at the bottom, identified as a solar boat, again made of gold, but originating from a different source. Path of Vega at winter solstice.png
 * 4) By the time the disc was buried it also had 38 to 40 holes punched out around its perimeter, each approximately 3 mm in diameter. The exact number is obscured by damage to the disc edge.

Significance


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 disc presents this knowledge in the form of a portable object. The disc may have had both a practical astronomical purpose as well as a religious significance.

The depiction of the Pleiades on the disc in conjunction with a crescent moon has been interpreted as representing a calendar rule for synchronising solar and lunar calendars, enabling the creation of a lunisolar calendar. This rule is known from an ancient Babylonian collection of texts with the title MUL.APIN. According to one of the seven rules in the compendium, a leap month should be added when the Pleiades appear next to a crescent moon a few days old in the spring, as depicted on the disc. This conjunction occurs approximately every three years. Harald Meller suggests that knowledge of this rule may have come from Babylonia to Central Europe through long-distance trade and contacts, despite it being attested earlier on the Nebra disc than in Babylonia. Baltic amber beads have been found in a foundational deposit under the large ziggurat of Aššur in Iraq dating from c. 1800-1750 BC, indicating that a connection existed between both regions when the Nebra disc was created. However some Assyriologists and astronomers have rejected the comparison of the Nebra Disc with MUL.APIN.



The number of stars depicted on the disc (32) is also thought to be significant, possibly encoding the calendar rule numerically. Firstly, the conjunction of lunar crescent and Pleiades depicted on the disc occurs after 32 days following the last "new light" (the first visible crescent moon of the month), and not before. Secondly, because a lunar year (354 days) is eleven days shorter than a solar year (365 days), 32 solar years is equal in length to 33 lunar years (with an error of only two days). That is, 32 x 365 = 11680 days, and 33 x 354 = 11682 days. This 32 solar-year cycle may be represented on the disc by 32 stars, plus the sun (or full moon), adding up to 33.

The archaeologist Christoph Sommerfeld has argued that the disc encodes knowledge of the 19-year lunisolar Metonic cycle. According to Sommerfeld the Metonic cycle is similarly encoded on the disc of the Trundholm sun chariot, dating from c. 1500 BC. The Metonic cycle is also thought to be encoded on the Late Bronze Age Berlin Gold Hat, which features a band of 19 "star and crescent" symbols.

Some authors have argued that the number of pin holes around the rim of the disc (approximately 38 to 40) has an astronomical significance. The exact number is not known due to damage to the disc.

The Nebra disc has also been compared to a passage from the Greek poet Hesiod in Works and Days, written around 700 BC: "When the Pleiades, daughters of Atlas, are rising, begin your harvest, and your ploughing when they are going to set. Forty nights and days they are hidden and appear again as the year moves round, when first you sharpen your sickle. This is the law of the plains, and of those who live near the sea, and who inhabit rich country, the glens and hollows far from the tossing sea,—strip to sow and strip to plough and strip to reap, if you wish to get in all Demeter's fruits in due season, and that each kind may grow in its season."



A depiction of a sun and crescent moon similar to the Nebra disc appears on a gold signet ring from Mycenae in Greece, dating from the fifteenth century BC. Beneath the sun and moon is a seated female figure holding three opium poppies in her hand, she is identified as a goddess of nature and fertility, with a double-axe and celestoal symbols, possibly the Minoan poppy goddess, or an early form of the goddess Demeter. Opium poppy has also been found in settlements of the Unetice culture. According to Kristiansen and Larsson (2005), imagery similar to that found on Mycenaean signet rings also appears in Nordic Bronze Age petroglyphs from the Kivik King's Grave in Sweden, dating from the sixteenth to fifteenth centuries BC.

Archaeoastronomist Emília Pásztor has argued against a practical astronomical function for the disc. According to Pásztor "the close agreement of the length of the peripheral arcs with the movement of the sun's risings or settings might be a pure coincidence". This claim is undermined by the finding of a similar feature on the roughly contemporary gold lozenge from Bush Barrow at Stonehenge, where the acute angles of the overall design (81°) are equal to the angle between the solstices at the latitude of Stonehenge. According to Euan MacKie (2009) "The Nebra disc and the Bush Barrow lozenge both seem to be designed to reflect the annual solar cycle at about latitude 51° north." MacKie further suggests that both the Nebra disc and Bush Barrow lozenge may be linked to the solar calendar reconstructed by Alexander Thom from his analysis of standing stone alignments in Britain. Both the Nebra sky disc and Bush Barrow lozenge were made with gold from Cornwall, providing a direct link between them. According to the archaeologist Sabine Gerloff the gold plating technique used on the Nebra sky disc also originated in Britain, and was introduced from there to the continent.



Authenticity
There were some initial suspicions that the disc might be an archaeological forgery. Peter Schauer of the University of Regensburg, Germany, argued in 2005 that the Nebra disc was a fake and that he could prove that the patina of the disc could have been created with urine, hydrochloric acid, and a blow torch within a short amount of time. He had to admit in court that he had never held the disc in his own hands, unlike the eighteen scientists who had examined the disc. Scientific analyses of the patina (or corrosion layer) have confirmed its authenticity.

Richard Harrison, professor of European prehistory at the University of Bristol, stated in a BBC documentary that "When I first heard about the Nebra Disc I thought it was a joke, indeed I thought it was a forgery", due to the extraordinary nature of the find, although he had not seen the sky disc at the time. The same documentary presented scientific analyses confirming the authenticity of the disc.

A paper published in 2020 by Rupert Gebhard and Rudiger Krause questioned the Early Bronze Age dating of the Nebra disc and proposed a later Iron Age date instead. A response paper was published in the same year by Ernst Pernicka and colleagues, rejecting the arguments of Gebhard and Krause. Scientific analyses of the disc, the items found with the disc, and the find spot have all confirmed the Early Bronze Age dating.

Exhibition
The disc was the centre of an exhibition entitled Der geschmiedete Himmel (German "The forged sky"), showing 1,600 Bronze Age artefacts, including the Trundholm sun chariot, shown at Halle from 15 October 2004 to 22 May 2005, from 1 July to 22 October 2005 in Copenhagen, from 9 November 2005 to 5 February 2006 in Vienna, from 10 March to 16 July 2006 in Mannheim, and from 29 September 2006 to 25 February 2007 in Basel.

On 21 June 2007, a multimedia visitor centre was opened near the discovery site at Nebra.

The disc is part of the permanent exhibition in the Halle State Museum of Prehistory (Landesmuseum für Vorgeschichte) in Halle.

The disc was on display at the British Museum in London as part of The World Of Stonehenge Exhibition from 17 February to 17 July 2022. The disc was on display at the Drents Museum in Assen from 6 August to 18 September 2022.

Replica on the ISS
In November 2021, a replica of the Nebra Sky Disc was launched to the International Space Station on the Crew-3 mission, taken by German astronaut Matthias Maurer. Maurer, who was part of the European mission Cosmic Kiss, designed the mission's patch with inspiration from the Nebra Sky Disk, as well as the Pioneer plaques and Voyager Golden Records that were sent into the unknown carrying messages from Earth.

Legal issues
The state of Saxony-Anhalt registered the disc as a trademark, which resulted in two lawsuits. In 2003, Saxony-Anhalt successfully sued the city of Querfurt for depicting the disc design on souvenirs. Saxony-Anhalt also successfully sued the publishing houses Piper and Heyne over an abstract depiction of the disc on book covers. The Magdeburg court assessed the case's relevance according to German copyright law. The defenders argued that as a cult object, the disc had already been "published" approximately 3,500 years earlier in the Bronze Age and that consequently, all protection of intellectual property associated with it has long expired. The plaintiff, on the other hand, argued that the editio princeps of the disc is recent, and according to German law protected for 25 years, until 2027. Another argument concerned the question of whether a notable work of art may be registered as a trademark in the first place. The Magdeburg court decided in favour of the State of Saxony-Anhalt.

The case was appealed and on the basis of decisions from the Oberlandesgericht Düsseldorf in 2005 and the Federal Court of Justice in 2009, the initial ruling was overturned and the German Patent and Trademark Office withdrew the trademark rights. Thereafter, the state of Saxony-Anhalt registered the design of the disc as a trademark with the European Union Intellectual Property Office.

In 2023, the state of Saxony-Anhalt filed a DMCA take down notice requesting removal of nine images of the Nebra sky disc from Wikimedia Commons, asserting that they were the "owner of the exclusive copyright in the Sky Disk of Nebra". Wikimedia Deutschland, a chapter of the Wikimedia Foundation, subsequently filed a DMCA counter-notice stating that since the implementation of Article 14 of the Directive 2019/790 of the European Parliament, there can be no such copyrights on reproductions of visual works that are in the public domain.