The map was discovered by scholars studying Christian texts written on an old piece of parchment using a method known as multispectral imaging in which image data across different ranges of the electromagnetic spectrum is captured to study objects.
The parchment they were studying was from the Codex Climaci Rescriptus, a collection of ancient texts found in Sinai, Egypt, which date back to the sixth century. The collection is known as a palimpsest manuscript, which means that the parchment that was used to write on had been erased and re-used.
Palimpsests are interesting to study because they often contain traces of the erased writing underneath the newer texts.
The Codex Climaci Rescriptus has original texts copied around the sixth century, with later texts copied around the ninth and tenth centuries, according to the Museum of the Bible.
While studying part of the material in 2012, University of Cambridge undergraduate student Jamie Klair noticed that some of the undertext seemed to be astronomical in nature. Pages were later re-analyzed by researchers at the Early Manuscripts Electronic Library in California, the Lazarus Project, and the University of Rochester using multispectral imaging and computer algorithms.
Then, in 2021, University of Cambridge biblical historian Peter Williams identified astronomical measurements.
The measurements were found to be fragments of the star catalogue composed by Greek astronomer Hipparchus during the second century BCE—the oldest known attempt to work out the precise position of the stars and give them coordinates, according to the French National Centre for Scientific Research (CNRS).
Victor Gysembergh, a CNRS science historian and co-author of a study outlining the discovery, told Newsweek: “The discovery of fragments from Hipparchus’ Star catalogue is a major breakthrough for the history of astronomy.
“It shows the precision of his naked-eye astronomical measurements to an order of one degree. It affords us a look inside ancient astronomers’ observatories: for instance, it shows that Claudius Ptolemy composed his own, later star catalogue by combining several sources of observation.
“More generally, this is a unique document of the birth of science, as a collective endeavor to measure and predict the world. I hope that this document will stimulate people to think in new ways about the history of ancient astronomy, since much of the new evidence it contains remains open to interpretation.”
Gysembergh said it was “very likely” that other historical works of science as well as works of history and philosophy will be discovered in the future by studying hidden text in old, reused parchment using multispectral imaging.
“This technology is non-destructive and has already allowed several other major discoveries in palimpsests over the past twenty or thirty years,” Gysembergh said. “Yet it has only been applied to a small fraction of the palimpsests preserved across the world.”
The study by Gysembergh and colleagues was published in the Journal for the History of Astronomy on October 18, 2022.
