Around 130 BC, Hipparchus of Rhodes produced the first comprehensive Greek catalogue of stellar positions. Roughly how many stars did he catalogue?
The Hipparchian catalogue contained approximately 850 stars, with positions in ecliptic coordinates accurate to about one degree and brightnesses on a 1-to-6 magnitude scale (the direct ancestor of the modern stellar magnitude system). The catalogue itself was lost; it survives substantially through inclusion in Ptolemy's *Almagest* (c. 150 AD), where Ptolemy substantially preserved Hipparchus's data with minor updates. A 2022 multispectral imaging project at St Catherine's Monastery in Sinai recovered fragments of the original Hipparchian Greek text from a palimpsest — the first direct recovery of any portion of the catalogue. Telescopes were 1,700 years in the future.
Read the full story →Hipparchus of Rhodes catalogued a thousand stars, invented trigonometry, discovered the precession of the equinoxes, and may have built the original of the Antikythera mechanism. Almost none of his writing survives.
Related questions
- The very slow westward drift of the celestial coordinate system relative to the fixed stars — the *precession of the equinoxes* — was first detected around 130 BC by an astronomer comparing his own star measurements with records from 150 years earlier. Who?
- What major astronomical phenomenon did Hipparchus of Rhodes discover around 130 BC?
- What ultimately happened to the bronze of the fallen Colossus of Rhodes?
- What was the Antikythera mechanism designed to do?