Ancient Science · Part 15 · Alexandria · B2
Hipparchus: A New Star, a Catalogue and the Slow Turning of the Sky
Part 15 of Ancient Science: Hipparchus saw a star where none had been before, and made the first catalogue of the stars so that the future could check them. Comparing his positions with older records, he found that the whole sky had slowly turned. Sophia shows what he found, how his lost catalogue was partly found again in 2022, and why records matter. Had moved, had observed, by the time, with Philo, Sophia, Marcos and Demetria.
Tonight, the greatest astronomer of the Greek world before Ptolemy: Hipparchus. He saw a star where no star had been before.
A new star? Stars don’t change. They are fixed. Everybody knows that.
That is exactly what Hipparchus began to doubt. So he did something nobody had done before: he made a list of the stars, with their positions, so that people in the future could check whether anything had changed.
Hipparchus was born in Nicaea, in what is now Turkey, and did most of his work on the island of Rhodes, between about 160 and 127 BCE. He wrote many books, but only one survives: a commentary criticising a popular poem about the constellations. Everything else we know from later writers, especially Ptolemy, who admired him.
Hipparchus measured the length of the year more exactly than anyone before him, and calculated the distance of the moon: about sixty times the Earth’s radius, which is close to the truth. He used old Babylonian records of eclipses, going back centuries, to test his theories.
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