Lost ancient Greek star catalog decoded by particle accelerator

"Before telescopes, ancient Greek astronomers relied on naked-eye observations of the night sky to understand the universe around them. The meticulous star catalog belonging to one of the best of these observers, Hipparchus, was long thought to be lost to time, but a hidden copy survived centuries. Erased and buried beneath layers of other text in a medieval codex, the catalog was nearly unreadableuntil now. Researchers say they have finally been able to decode some of the lost text"

"They hope their analysis will shed light on what the earliest astronomers' methods were and how Hipparchus's work influenced later scientists. Since this star catalog is so important for understanding the birth of science, it made us want to pull out all the stops, says Victor Gysembergh, a researcher at the French National Center for Scientific Research (CNRS), who led the experiment. What we've been seeing is amazing in comparison to previous imaging."

"The term palimpsest comes from ancient Greek words meaning scraped again and denotes a manuscript that has had its words erased and written over. Such erasure was a common practice throughout history to repurpose expensive parchments, but it poses a unique challenge for scholars hoping to uncover lost texts. For centuries, scientists have tried different lighting and chemicals to bring back erased texts."

A hidden copy of Hipparchus's star catalog survived erased beneath layers of other text in a medieval palimpsest. Synchrotron imaging, a particle accelerator technique, enabled decoding of some erased entries including constellation names and measurements. The palimpsest, Codex Climaci Rescriptus, contains portions dating from the fifth through the ninth or tenth centuries CE. Palimpsest erasure was a common practice to repurpose expensive parchments, which complicates recovery of underlying texts. Prior recovery attempts used varied lighting and chemical methods. The decoded material can illuminate early astronomical methods and Hipparchus's influence on later scientists.

Read at www.scientificamerican.com