The Carso Plateau (Karst) is a limestone region between Slovenia and Italy famous for its pine forests and caves, among which Vilenica, Skocjan or the Grotta Gigante, the largest tourist cave in the world, which is located in the province, stand out. from Trieste.
Just three kilometers from the Triestine grotto is the Castelliere di Rupinpiccolo, an Iron Age fortification with a wall between three and four meters thick. Although the walls are currently three meters high, experts believe that while they were in use (between 1800 and 400 BC) they reached seven meters.
Near the entrance to this imposing square, one of the most important castles in the area, two large circular stones about 50 centimeters in diameter and 30 centimeters deep were found. One of them is believed to represent the sun. The other has always been an enigma. Until now.
This second disk, which has surprising marks on its surface, had puzzled dozens of researchers. But Italian archaeologist Federico Bernardini, from Ca' Foscari University in Venice, had a hunch and contacted astronomer Paolo Molaro, from the Institute of Astrophysics in Trieste.
They both came to the conclusion that what they had before them was the oldest celestial map ever discovered. As explained in an article published in Astronomische Nachrichten, the oldest still active astronomy magazine in the world, the engravings represent with remarkable precision the stars of Scorpio, Orion, the Pleiades and Cassiopeia.
“About two years ago, Federico Bernardini, whom I didn't know, contacted me, telling me that he needed an astronomer,” Molaro recalls in a statement. “He seemed to have identified the constellation of Scorpio in a stone from the Karst. My first reaction was disbelief, given that the southern part of Scorpio is just above the horizon at our latitudes. Then, upon discovering that the precession of the equinoxes (the change in the orientation of the Earth's axis of rotation) elevated it by about 10-12 degrees, I began to delve deeper into the question... Thus I identified Orion, the Pleiades and, in the background, Cassiopeia. All points present except one," he recalls.
The signs identified by Molaro and Bernardini are 29 in total: 24 on one side of the stone and five on the other. Although they are irregularly distributed, they all have a common orientation, as if they were engraved by the same person armed with a hammer and a rudimentary metal chisel with a 6-7 mm tip, the scientists suggest.
A few kilometers away, in the Castelliere di Elleri, a bronze instrument was discovered (which is today kept in the Archaeological Museum of Muggia) and which is compatible with the marks. Hence the researchers came to the conclusion that the signs were not works of nature nor were they there by chance.
Someone recorded them at least 2,400 years ago, when the Castelliere di Rupinpiccolo was still fulfilling its fortification task. And when the stars of Scorpio were still shining on the horizon, as Paolo Molaro has been able to reconstruct. One star in particular, Sargas (also called Theta Scorpii) is no longer visible from the castle today.
Despite the success of the specialists, there is still one point that has not been identified. The star map shows considerable care in the execution, which has led researchers to believe that this last mark is also there on purpose representing a supernova or what is even more likely, a “failed supernova.”
This is one of those objects that astronomers call transient: at a certain moment they appear and then disappear without a trace. If this were the case, Molaro and Bernardini suggest, there could be a black hole today at that point in the sky that was etched in the stone.
The oldest known representation of the night sky is the Nebra disk, a gold-inlaid bronze object discovered in Germany and dated to around 1600 BC. that pointed to the Sun, the Moon and the Pleiades. Even so, it is not a real map, but rather a symbolic representation.
To obtain maps faithful to reality we have to wait until the 1st century BC, at a time when the charts were probably derived from the catalog of elliptical coordinates of 850 stars made by Hypparcos and dating back to the year 135 BC.
Little is known about the inhabitants of the Castelliere di Rupinpiccolo from 2,500 years ago, other than that they did not know how to write, which adds more mystery to this album. But what seems evident is that they showed a surprising curiosity about astronomy already in protohistoric Europe.
