Munich

Astronomical claim: did Bronze Age people identify the seasons by the stars? Credit: H. J. LIPTAK/SAXONY ANHALT DEPT ARCHAEOL

A bronze disc depicting the Sun, Moon and stars, which went on public exhibition in Germany this month, has sparked a debate about the astronomical expertise of Bronze Age Europeans. Intrigued archaeologists and astronomers can thank the police, who recovered the artefact after it was stolen from a site at Sangerhausen in the state of Saxony Anhalt, 100 kilometres west of Leipzig.

The gold-decorated disc is on show at the State Museum of Prehistory in Halle. Some 3,600 years old, it may be the first 'scientific' representation of the sky of central Europe, claims Wolfhard Schlosser, an astronomer at Ruhr University in Bochum. He believes that the disc represents the constellation Pleiades.

At the time the disc was made, Pleiades was not visible from central Europe in spring. So the constellation's disappearance might have been used to herald the season's arrival. Alix Henseler, an expert on the Bronze Age at the Museum of Prehistory in Berlin, says the disc suggests that “people living in middle Europe in the Bronze Age were able to draw seasonal conclusions from observations of stars”.

But other astronomers are not convinced. “The bronze disc is clearly a remarkable object, but as an astronomical piece it is very primitive,” says Owen Gingerich, an expert in the history of astronomy at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. He disputes whether the pattern of stars represents a specific constellation.

Experts can count themselves lucky that they are able to debate the object's significance at all. In 1998, two amateur archaeologists excavated the disc and sold it to a dealer for 15,000 euros (US$13,300) — although under German law all such finds belong to the federal republic. The dealer unsuccessfully tried to sell it to the Berlin museum.

A go-between, who later claimed that she had wanted the disc to stay in Germany, then sold it to a Düsseldorf schoolteacher. Believing that Harald Meller, chief of Saxony Anhalt's department of archaeology, might want to buy the disc for the state, the go-between invited him to meet the teacher in February this year. But Meller was already working closely with German police, and both the teacher and the go-between were arrested. They have yet to be charged.