It’s a real time travel. This text ancient astronomy is almost 2200 years old: it is an extract from the star catalog of the Greek astronomer Hipparchus and it is the oldest known human attempt to measure the position of stars in the sky. These two pages of ancient astronomy have just been found by a Franco-British team involving the National Center for Scientific Research (CNRS) in a Christian manuscript dating from the Middle Ages kept at the Orthodox monastery of Saint Catherine, on the Sinai Peninsula. , in Egypt.
Part of lost star catalog of Hipparchus found lurking under medieval codex. Multispectral imaging revealed hidden original text on Codex Climaci Rescriptus. https://t.co/Xwi5hgtSKK
— Jennifer Ouellette (@JenLucPiquant) October 20, 2022
These pages were in fact hidden by other lines of writing, because they had been voluntarily erased, so that the parchment could be used again as a support for a new author. the palimpsest, manuscript consisting of a parchment already used, was indeed the recycling of the time. Historians have so far only known of the existence of these astronomical observations of Hipparchus through other writings, but there they were finally able to find and read them.
These researchers were therefore able to read a completely erased text, on which we have rewritten, thanks to multi-spectral imaging techniques. The principle is to take photos of the text in different wavelengths and then recombine them by computer, according to Victor Gysemberg, CNRS researcher at the Léon Robin center in Paris, one of those who contributed to this discovery. In certain light wavelengths, traces of erased ink may reappear.
And so it’s a technique that makes visible traces, writings that had disappeared. “I would never have hoped to witness this discovery in my lifetime”, says the researcher. After reading these two pages found, historians were then able to see that Hipparchus’ calculations on the position of the stars, made around minus 150 BC, with the naked eye, were accurate to the nearest degree. Even more accurate than other astronomical measurements made a few centuries later. This imaging technique could make it possible to bring back other missing documents. Old medical treatises, pages written by Plato or Archimedes, old illustrious herbaria have also been able to reappear.
However, this multispectral imaging technique is quite expensive, but it is still in its infancy. It is still possible to technically improve the quality of the photos, the image resolution, the spectral analysis… Scientists and historians therefore hope to be able to decipher in the years to come hundreds of palimpsests, these reused parchments, which sleep in libraries.