Within a setting characterized by an array of metallic conduits and an intricate network of wiring, two investigators direct attention to vivid orange undulations displayed on a digital interface. These peculiar markings represent a poetic composition in archaic Greek, focusing on celestial occurrences, now elucidated for human observation after an interval spanning nearly one and a half millennia.
“Embedded within is an addendum containing the celestial coordinates of the stars referenced in the verse, accompanied by rudimentary depictions of astronomical charts,” states Minhal Gardezi, a physicist affiliated with the University of Wisconsin–Madison.
Gardezi is an integral member of a research contingent operating at the SLAC National Accelerator Laboratory, situated in Menlo Park, California, with the objective of deciphering these star charts. The provenance of these celestial maps traces back to a compendium compiled by the Hellenistic astronomer Hipparchus of Nicaea, dating to approximately 150 B.C. This work was subsequently replicated around the 6th century A.D. Inscribed on prepared animal skin, the poem and its accompanying charts were later subjected to erasure and overwritten with novel script. Through the application of high-intensity X-rays emitted from SLAC’s particle accelerator to the vellum, the hitherto imperceptible inscriptions are once again brought to light.
Direct insights from antiquity are regrettably sparse. The majority of classical Greek scholarship was committed to papyrus, a medium that seldom withstands the ravages of time. Nearly all of Hipparchus’s literary output remains undiscovered, despite secondary accounts suggesting his role in the creation of an early stellar catalog and his contributions to the development of trigonometry. The manuscript housed at SLAC represents a profoundly valuable repository for scholars endeavoring to gain a more profound comprehension of the nascent stages of scientific inquiry over two millennia ago.
The dimensionality of this artifact measures approximately 18 by 21 centimeters, bearing a resemblance in size to a pocket-sized book. It is recognized as a palimpsest, a parchment crafted from the hide of goats or sheep, from which the original textual content was ablated and subsequently reimposed. This specific instance, known as the Codex Climaci Rescriptus, originates from Saint Catherine’s Monastery, located within the Sinai desert of Egypt. At some point during the 9th or 10th century, a monastic scribe repurposed the blank palimpsest – its prior text vitiated either by the monks or their predecessors – to record theological treatises.
Although the obliterated script is no longer discernible to the unaided eye, sophisticated imaging methodologies had previously achieved partial reconstruction of the concealed writing. This phenomenon is attributable to the absorption of ink’s chemical vestiges into the parchment, subtly altering its light-reflectant properties. By subjecting these faint imprints to diverse wavelengths of electromagnetic radiation – encompassing both the visible spectrum and adjacent regions – segments of the expunged text become recoverable.
To obtain a comprehensive realization, the researchers directed SLAC’s highly concentrated and potent X-rays, which vastly exceed the capabilities of visible light and can be a millionfold more intense than those employed in dental radiography, at the manuscript. Rigorous measures were implemented to preclude any degradation of the material. The X-rays induce excitation in the ink’s constituent chemical elements, prompting luminescence. “While imperceptible to the observer, their presence persists,” notes Uwe Bergmann, a fellow physicist at UW–Madison. The X-ray analysis successfully identified elevated calcium signatures within the older, concealed inscription compared to the overlying text.
The primordial literary stratum of the palimpsest comprises the poem “Phaenomena” authored by the ancient Greek poet Aratus of Soli. Conceived originally around 275 B.C., it delineates the heliacal risings and settings of various constellations. The anonymous scribe of the 6th century, who transcribed the poem onto the palimpsest, also incorporated supplementary sections akin to appendices, which detailed stellar positions relative to the constellations. The scholars ascertain these sections to be derived from Hipparchus due to the commensurate precision and distinctive coordinate framework aligning with subsequent historical accounts of his work.
Gardezi likens this practice to an editorial addition of annotations to a rendition of Shakespeare’s “Hamlet,” serving to “furnish edifying trivia, such as culinary suggestions pertinent to the play’s narrative.”
Having successfully retrieved fragmentary segments, the research collective now intends to conduct scans on the remaining palimpsests within the codex. Computational algorithms will be instrumental in further enhancing the textual and cartographic elements, thereby enabling the team to extract more substantive data from these sparse ideograms. The advanced imaging has hitherto contributed to resolving a protracted scholarly debate concerning whether the Greco-Roman Egyptian astronomer Ptolemy, who flourished during the 2nd century A.D., engaged in the appropriation of Hipparchus’s research. It has been substantiated that Ptolemy’s astronomical catalogs utilized Hipparchus’s work as a foundational reference but also incorporated material from alternative scholarly sources.
“This constitutes scholarly synthesis, not plagiarism,” asserts Victor Gysembergh, a coauthor of the study and a historian of science at CNRS in Paris. “This practice persists in contemporary scientific endeavors, wherein diverse sources are synthesized to achieve optimal data outcomes.”
Additional researchers anticipate the revelations that further palimpsests may hold. Preceding investigations by the same team, as reported by Graham George, a chemist at the University of Saskatchewan in Saskatoon, Canada, who was not affiliated with this project, unearthed descriptions of foundational calculus principles – widely believed to have originated in the late 17th century – within a 3rd-century B.C. transcription of Archimedes’ writings.
“The potential discoveries from the stellar cartography study remain an open question,” he posits. “I eagerly await the forthcoming findings.”
