Ancient 'Ritual Artifact' May Reveal Secrets of Deep Space

A mysterious ancient artifact could help reveal the whereabouts of a star that exploded as a supernova thousands of years ago and is no longer visible.

The artifact, which was found in Italy, is a stone disk featuring engravings that researchers believe form a celestial map of the night sky, according to a study published in the journal Astronomische Nachrichten.

In the study, the researchers identified several engravings on the disk that they said precisely match the locations of groups of stars visible in the night sky.

Intriguingly, the "ritual" stone may represent one of the oldest, if not the oldest, celestial maps ever discovered, according to the scientists, although further research is required to understand more about the object's nature.

The stone, which is about the size of a car tire, was found at the site of an ancient hill fort in Rupinpiccolo, northeastern Italy. These types of historic settlements are generally protected by massive stone walls and are known today as castellieri.

The castelliere at Rupinpiccolo appears to have been used as a fortification between 1800/1650 B.C. and 400 B.C. While it is not clear exactly how old the stone is, it is likely that the disk dates to some point in this period—making it at least 2,400 years old.

The stone disk features chisel marks that were produced by a human hand and do not look randomly distributed, according to the researchers. While they are spread out in an irregular fashion, they all have a common orientation, suggesting that they were engraved by the same person, who likely used some form of rudimentary chisel.

In total, researchers have identified 29 marks: 24 on one face of the stone and five on the other. Intriguingly, the scientists were able to use software to map these marks to specific groups of stars in the constellations of Scorpius, Orion and Cassiopeia, as well as the star cluster known as the Pleiades, based on how they appeared in the sky during the period when the castelliere at Rupinpiccolo was in use.

The researchers determined that it was highly unlikely the marks were arranged in such a way purely by chance, given the precision with which they matched the distribution of their respective stars.

However, one of the marks, located slightly north of Orion, proved to be problematic because the scientists could not identify it in the current night sky.

The unidentifiable mark looks like the others and therefore was probably made on purpose. To explain this, the researchers suggest it could represent a star in the Orion cluster that was present at the time the stone was carved but that later produced a supernova—cataclysmic explosions that occur when massive stars die—or, more likely, a failed supernova.

In the latter event, a star suddenly brightens like in the early stage of a supernova but the process does not progress as usual. Failed supernovas are thought to leave behind black holes as remnants.

If the mark on the stone does represent a failed supernova, the remaining black hole would not be visible today, but it could be detected using modern astronomical observations.

"The case of a failed supernova is really intriguing as one of the techniques to search for them is precisely to look for missing stars in the current sky, by using images taken at previous times," the authors wrote in the study. "This possibility offers a way to verify the proposed interpretation."

The researchers call for further studies to assess the proposed interpretation, which would shed light on the meaning of the stone disk.

"We regard this interpretation as a suggestion and we urge additional studies and searches of other astronomical evidence in the civilization of the castellieri to avoid fanciful interpretations," the authors said. "The discovery of the remnant of a failed supernova in the position of the unidentified mark to the north of Betelgeuse would prove our reading."

A precise date for the manufacturing of the stone disk has yet to be determined. But given that it is likely more than 2,400 years old at least, the stone may well be one of the oldest celestial maps ever discovered.

The earliest possible date of the disk is around 1800 B.C., but even considering the latest date of 400 B.C., the representation of the sky on the stone remains very old, compared with similar finds.

The oldest known depiction of the sky is possibly the Nebra disk—a bronze artifact found in Germany that has been dated to around 1600 B.C. and contains features generally interpreted as astronomical objects. But some researchers argue that the disk is more of a symbolic representation rather than a precise astronomical map. "Faithful" sky maps do not tend to appear until around the first century B.C., at least a few centuries after the latest date for the Rupinpiccolo disk.

Very little is known about the population that lived in the Rupinpiccolo hill fort, but the researchers suggest that the disk could have helped track the changing of the seasons. Thus, it could have been used to determine the appropriate time for agricultural tasks, upon which the survival of the castelliere would have depended.

The Rupinpiccolo hill fort was one of hundreds constructed by a civilization that existed in the wider region from around the year 2000 B.C. until the arrival of the Romans around 400 B.C.

Paolo Molaro, who is with the Astronomical Observatory of Trieste and one of the study's authors, told Newsweek, "The [latest] finding, if interpreted as a calendar, shows that they had some knowledge of the changing sky in relation to the seasons and of the needs of agriculture.

"Primitive man watched the sky," he continued. "This is shown by many examples in several civilizations, for instance in the rock paintings in the Lascaux cave, which date back to almost 20,000 years B.C. But what is unique in our stone is the effort to faithfully reproduce the position of the stars in the sky."

Update 1/5/24, 11:08 a.m. ET: This study was updated with comments from Paolo Molaro of the Astronomical Observatory of Trieste.