Skip to content
Wellsprings
Hipparchus

Hipparchus

c. 190 BCE–c. 120 BCE · Rhodes

Hipparchus of Nicaea (c. 190-c. 120 BCE), who worked largely on Rhodes, was a Greek astronomer and mathematician regarded as the greatest astronomical observer of antiquity. He discovered the precession of the equinoxes, compiled an influential star catalogue, and made foundational contributions to trigonometry. Most of his own writings are lost, but his results were transmitted and built upon by Ptolemy.

See Hipparchus’s journey on the map →

Did you know?

  • A Greek measured the Earth's 26,000-year wobble

    Around 129 BCE the astronomer Hipparchus compiled one of antiquity's first great star catalogues, and by comparing his star positions with observations recorded about 150 years earlier he detected the precession of the equinoxes — the slow wobble of Earth's axis that completes a full cycle only every ~26,000 years. He inferred a cycle tens of thousands of years long from barely a century and a half of records, by eye and without a telescope.

    How we know

    Hipparchus c. 190–120 BCE; catalogue c. 129 BCE, compared with Timocharis' observations (~150 years earlier) → discovery of precession; the modern cycle is ~25,800 years.

Life journeyclick any stop, or use ←/→

Stop 1 of 1

RhodesרודוסAegean (Greece)

We know they were here, but the specifics of what they did at this stop aren’t recorded yet in our corpus.

About Rhodes

Rhodes is the largest of the Dodecanese islands in the southeastern Aegean, off the southwest coast of Asia Minor. In the Hellenistic and Roman periods it was a renowned center of rhetoric, philosophy, and astronomy: the Stoic Panaetius was a native, the Stoic polymath Posidonius (himself born at Apamea) ran his school there, and the astronomers Hipparchus and Geminus worked on the island.

In Rhodes at the same time

Panaetius of Rhodes, Posidonius of Apamea

See other sages who lived in Rhodes→

In the same place & time

Sages whose lives overlapped with Hipparchus’s in the same cities, drawn from their recorded journeys.

The world in their lifetime

Thinkers and teachers of other traditions whose lives overlapped with Hipparchus’s — a glimpse of the wider world they lived in. Drawn purely from recorded birth and death years.

Works(1)