Particle accelerator decodes lost ancient Greek star catalog

Researchers led by Victor Gysembergh of CNRS used a synchrotron at SLAC National Accelerator Laboratory to decode erased ancient Greek text from the Codex Climaci Rescriptus, revealing star coordinates from astronomer Hipparchus dating back to around 150 B.C.bez-kabli
The X-ray technique detected calcium-rich traces from older ink beneath iron-rich medieval writing, allowing the team to identify references to the constellation Aquarius and descriptions of bright stars.greekreporter
The recovered data may help settle a centuries-old debate about whether the astronomer Ptolemy plagiarized Hipparchus’s work, with researchers expecting the codex to become the most complete repository of Hipparchus’s observations.scientificamerican

Scientists Recover Hipparchus Star Catalog Using X-ray Technology

Powerful X-rays from a particle accelerator have illuminated fragments of one of history’s most important astronomical documents—the lost star catalog of the ancient Greek astronomer Hipparchus—after lying hidden beneath medieval religious texts for more than a millennium.

Researchers working at SLAC National Accelerator Laboratory in Menlo Park, California, this month successfully decoded erased ancient Greek text from a manuscript known as the Codex Climaci Rescriptus, including star coordinates that date back more than 2,000 years.bez-kabli

Ancient Text Resurfaces Through Modern Science

The team, led by Victor Gysembergh of the French National Center for Scientific Research (CNRS), used a synchrotron—a type of particle accelerator that generates intense X-ray beams—to penetrate layers of ink on the 1,000-year-old parchment. The technique works because different inks leave distinct chemical signatures. While the visible medieval text contains high iron concentrations, the older Greek writing left calcium-rich residues that the X-rays could detect.scientificamerican

“Since this star catalog is so important for understanding the birth of science, it made us want to pull out all the stops,” Gysembergh told Scientific American. “What we’ve been seeing is amazing in comparison to previous imaging.”scientificamerican

The codex is a palimpsest—a document that was scraped clean and rewritten multiple times due to the high cost of parchment. Originally created by Christian monks in Egypt during the fifth or sixth century, the pages were later overwritten with Syriac religious texts.yahoo

Recovering Coordinates to the Cosmos

When researchers scanned 11 pages supplied by the Museum of the Bible in Washington, D.C., lines of ancient Greek began appearing on monitors. The team has already identified the Greek word for “Aquarius” and descriptions of “bright” stars in that constellation.greekreporter

Hipparchus, who worked around 150 B.C., is credited with creating one of the earliest systematic star catalogs and helping invent trigonometry. His original work was long thought lost, though his influence persisted through later astronomers.sciencenews

“There’s an appendix which includes coordinates of the stars discussed in the poem, and then little sketches of the star maps,” said Minhal Gardezi, a physicist at the University of Wisconsin–Madison involved in the project.sciencenews

Settling Historical Debates

The newly recovered data may help resolve a centuries-old debate about whether the Roman-Egyptian astronomer Ptolemy plagiarized Hipparchus’s work. Early analysis suggests Ptolemy used Hipparchus’s catalog as a reference but also incorporated material from other sources.sciencenews

“That’s not plagiarism, that’s science,” Gysembergh said. “We still do that today, combining sources to get the best data possible.”sciencenews

When their analysis is completed, researchers expect the Codex Climaci Rescriptus to become the most complete repository yet of Hipparchus’s observations—offering a clearer window into how ancient astronomers mapped the cosmos without telescopes.scientificamerican