Antiquity specialists had come to doubt it. But Hipparchus was well, in the IIe century BC, the author of a catalog listing the positions of the stars visible from the northern hemisphere. A Franco-British team has just provided tangible proof of this by deciphering an astronomy text in Greek, hidden under the writings of a medieval parchment.
Victor Gysembergh, Emanuel Zingg and Peter J. Williams, respectively researchers at the CNRS, Sorbonne University and Tyndale House in Cambridge, state in the Journal for the History of Astronomy that this description of the constellation Corona Borealis is based on observations from the time of the scientist. An index which, put in relation with others, would attest, according to them, to the reality of this first attempt at a rigorous inventory of the stars…
The case is important. Isn’t Hipparchus of Bithynia (in Turkey today) one of the greatest astronomers of Mediterranean antiquity? “While his predecessors were content to depict the constellations or to count the stars included in them, he was the first among the Greeks to give precise angular positions of a large number of stars on the sphere of the sky, by resorting to an orthogonal coordinate systemexplains science historian James Evans of the University of Puget Sound (California). This helped transform the purely descriptive and empirical science that was astronomy into a predictive discipline based on calculation. »
Inspiration of Ptolemy
Other advances are attributed to him. In particular the discovery of the precession of the equinoxes. This modification, from one year to another, of the place occupied in the Zodiac by the Sun, at the time of the vernal equinox, is caused by variations in the direction of the axis of rotation of the Earth. It is accompanied by an apparent movement of the celestial vault whose stars shift little by little, at the rate of 1 degree in longitude per 71.58 years and according to a cycle of… 25,769.42 years. The astronomer would have identified and approximately measured the phenomenon.
“Lastly and above all, Hipparchus is known to have inspired, around 250 years later, the Egyptian scholar Claudius Ptolemy who cites his work and his catalog in his Almageste »says Anne Tihon, professor emeritus at the Catholic University of Louvain-la-Neuve (Belgium), who recently exhumed from a palimpsest kept in the Vatican, one of the so-called “easy” astronomical tables designed by Ptolemy: “Written in IIe century AD, this treatise synthesizing all the knowledge accumulated by the Babylonians, the Greeks and the Egyptians, providing tables and an inventory of the positions of 1,022 stars, will become the reference work for astronomy Western culture when it was rediscovered in the Middle Ages through translations into Latin and Arabic languages. And this for centuries and until the formulation of the theory of heliocentrism by Copernicus and the invention of Galileo’s telescope.. That is to say at the end of the Renaissance.
You have 65.03% of this article left to read. The following is for subscribers only.