The Nebra sky disk is one of the most significant archaeological finds in German history. Discovered by two looters in 1999, the artifact was fashioned by prehistoric humans who inlaid on a blue-green patina gold symbols that represent the Moon, the Sun, stars, and maybe even the Milky Way.

The State Museum of Prehistory in Halle (Saale) took over ownership of the disk in 2002 and since then there’s been a major debate about its age. The artifact itself can't be dated and how the disk was found is nebulous: the looters claim they found the disk together with swords, axes, and armlets dated to the Bronze Age, roughly between 2200 and 1600 BCE. If this is correct, the disk would be the oldest-known concrete depiction of the night sky.

However, two researchers don’t believe the dating, saying no item like the disk has been found in the Bronze Age. In the journal Archäologische Informationen, the team instead suggests the Nebra disk dates to the Iron Age, making it roughly 1,000 years younger than previously thought.

The researchers provide several reasons for their conclusion. The looters' tale on how they found the disk (and its subsequent damage) doesn’t match what can be reconstructed from the artifact itself. The scientists also compared the disk's metals with that of the other objects found in the same location. In other hoards, there is often evidence that all the objects were crafted from raw material collected from the same place. No such similarity is seen here. The artifacts were sourced from material spread out across the Eastern Alps.

"In our view, the results obtained so far speak against the finds belonging together," Professor Rüdiger Krause, co-author and expert on metal analyses, said in a statement.

The team's recent work is harshly rejected by the State Office for Archeology in Saxony-Anhalt, the region where the disk was found.

"Gebhard and Krause put forward several key points as a platform for this thesis," the statement reads. "The colleagues not only ignore the abundance of published research results in recent years, their various arguments also are easily refuted. In particular, the correlation of the Sky Disc with the other discoveries of the hoard, whose Bronze Age age is not in question, is put in doubt. Claims are that the soil attachments on the Sky Disc do not correspond with those of the other findings and that the geochemical analyzes of the metals do not support their coherence. Both of these statements are demonstrably incorrect."

Although the team say the disk's depictions are closer to artifacts found in the 5th century BCE, such as the sword from Allach (Munich), they do not doubt the disk is authentically prehistoric, unique, and of immense scientific value.