A map of the night sky created by the ancient Greek astronomer Hipparchus was recently discovered at St. Catherine Monastery on the Sinai Peninsula in Egypt.
Hidden beneath Christian texts, scholars have discovered what seems to be part of the long-lost star catalog of Hipparchus—believed to be the earliest known attempt to map the entire sky.
Scholars have been searching for Hipparchus’s catalog for centuries. James Evans, a historian of astronomy at the University of Puget Sound in Tacoma, Washington, describes the find as “rare” and “remarkable.”
Map of the sky manuscript in ancient Greek
The extract has been published online this week in the Journal for the History of Astronomy.
Evans says it proves that Hipparchus, often considered the greatest astronomer of ancient Greece, really did map the heavens centuries before other known attempts.
It also illuminates a crucial moment in the birth of science, when astronomers shifted from simply describing the patterns they saw in the sky to measuring and predicting them.
The manuscript came from the Greek Orthodox St Catherine’s Monastery, but most of its 146 leaves, or folios, are now owned by the Museum of the Bible in Washington D.C.
Nature reports that the folios revealed astronomical material and star coordinates. The catalog states the length and breadth in degrees of the constellation Corona Borealis, the northern crown, and gives coordinates for the stars at its extreme north, south, east, and west.
Several lines of evidence point to Hipparchus as the source, beginning with the idiosyncratic way in which some of the data are expressed, Nature says.
Most crucially, the precision of the ancient astronomer’s measurements enabled the team to date the observations.
The phenomenon of precession in which Earth slowly wobbles on its axis by around one degree every seventy-two years means that the position of the fixed stars slowly shifts in the sky.
The researchers were able to use this to check when the ancient astronomer must have made his observations. They found that the coordinates fit roughly 129 BC during the time when Hipparchus was working.
Ancient Greek Hipparchus founder of trigonometry
Hipparchus is considered the founder of trigonometry but is most famous for his incidental discovery of the precession of the equinoxes.
He was born in Nicaea, Bithynia, and probably died on the island of Rhodes, Greece. He is known to have been a working astronomer between 162 and 127 BC.
Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity.
He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive.
For this reason, he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and by Meton of Athens (fifth century BC), Timocharis, Aristyllus, Aristarchus of Samos, and Eratosthenes among others.
He developed trigonometry and constructed trigonometric tables, and he solved several problems of spherical trigonometry. With his solar and lunar theories and his trigonometry, he may have been the first to develop a reliable method to predict solar eclipses.
His other noteworthy achievements include the discovery and measurement of Earth’s precession, the compilation of the first comprehensive star catalog of the Western world, and possibly the invention of the astrolabe, also of the armillary sphere that he used during the creation of much of the star catalog.