The Greek astronomer Hipparchus wrote a Star Catalogue between the years 170 and 120 BC – however, the astronomical text has been lost for centuries. This has now changed, as a team of researchers has uncovered the partially-erased text in a medieval manuscript.
Researchers from the CNRS, Sorbonne University and Tyndale House were able to make the discovery during their examination of the Codex Climaci Rescriptus ‒ a book made up of parchments that were erased and then rewritten on, also known as a palimpsest. The original writings in the Codex date from the 5th century AD, but were then erased and written over in the 9th or 10th century.
Researchers and students at Tyndale House, which is affiliated with Cambridge University, began examining the manuscript in 2012, trying to decipher words that had been erased. They soon found writing about astronomy, which prompted further research and eventually multispectral imaging photography, which could show more writing not visible to the naked eye.
A section of the lost text has been transcribed. Translated into English, it states:
Corona Borealis, lying in the northern hemisphere, in length spans 9°¼ from the first degree of Scorpius to 10°¼8 in the same zodiacal sign (i.e. in Scorpius). In breadth it spans 6°¾ from 49° from the North Pole to 55°¾. Within it, the star (β CrB) to the West next to the bright one (α CrB) leads (i.e. is the first to rise), being at Scorpius 0.5°. The fourth9 star (ι CrB) to the East of the bright one (α CrB) is the last (i.e. to rise) [. . .]10 49° from the North Pole. Southernmost (δ CrB) is the third counting from the bright one (α CrB) towards the East, which is 55°¾ from the North Pole.
This information helped to confirm that this was the writing of Hipparchus.
The fragments of the Star Catalogue are the oldest known to date and bring major advances in its reconstruction. Firstly, they refute a widespread idea that Claudius Ptolemy’s Star Catalogue is merely a “copy” of Hipparchus’ as the observations of the four constellations are different. Furthermore, Hipparchus’ data are verified to the nearest degree, which would make his catalogue much more accurate than Ptolemy’s, even though it was composed several centuries earlier.
For the research team this major discovery sheds new light on the history of astronomy in antiquity and on the beginnings of the history of science. Above all, it illustrates the power of advanced techniques, such as multispectral imaging, whose application on illegible palimpsests could save numerous lost texts on philosophy, medicine or horticulture from oblivion.
The article, “New evidence for Hipparchus’ Star Catalogue revealed by multispectral imaging,” by Victor Gysembergh, Peter J. Williams, and Emanuel Zingg, appears in the Journal for the History of Astronomy, Vol. 53:4 – click here to read it.
Top Image: Image: A section of a page from Codex Climaci Rescriptus during the multispectral analysis. Museum of the Bible (CC BY-SA 4.0). Photo by Early Manuscripts Electronic Library/Lazarus Project, University of Rochester; multispectral processing by Keith T. Knox. Courtesy Tyndale House