World’s oldest known star map found hidden in medieval manuscript

Over 2,100 years ago, the Greek astronomer Hipparchus mapped the stars – and for a long time this was considered humanity’s first attempt to assign numerical coordinates to stellar bodies. But despite its fame, the treaty’s existence was known only from the writings of another ancient astronomer named Claudius Ptolemy, who compiled his own celestial inventory some 400 years later.

So far, that is.

Researchers believe they have found fragments of Hipparchus’ lost historical document hidden in a book of medieval Greek manuscripts.

“This new evidence is the most reliable to date and enables major progress in reconstructing Hipparchus’ star catalog,” reads a study of the find published in the journal History of Astronomy this week. This discovery could shed new light on the history of astronomy.

Hipparchus, also known as the father of trigonometry, is often considered the greatest astronomer of ancient Greece. Portions of his star map appear to have appeared in the Codex Climaci Rescriptus, a book of Syriac texts in which pages of parchment were erased so they could be rewritten, but still bear visible traces of their earlier form. This particular palimpsest is at the Greek Orthodox Monastery of St. Catherine on Egypt’s Sinai Peninsula.

Teams from the Early Manuscripts Electronic Library and the Rochester Institute of Technology-based Lazarus Project revealed the erased text and numerals using different wavelengths of light, a technique known as multispectral imaging.

Researchers from the Sorbonne University and the University of Cambridge were then able to decipher the descriptions of four constellations. Not only did this appear to uncover Hipparchus’ cartography, but the team also claims that the newly revealed digital evidence is highly consistent with real stellar coordinates.

This would make Hipparchus’ catalog more accurate than Ptolemy’s much more recent version, although the researchers acknowledge that they are working with a small sample size and that significant errors could exist in parts of Hipparchus’ star catalog that did not survive.

As advanced digital technologies continue to recover vital pieces of cultural heritage lost through damaged and deteriorated records or deliberate erasure, scientists say the Codex Climaci Rescriptus could yet reveal even more star sightings of Hipparchus.