ASTRONOMER, GEOGRAPHER, METEOROLOGIST

Life
Stoic philosopher with Neoplatonist tendencies, Posidonius was born in Apamea, in Syria. He studied in Athens, with Panaetius of Rhodes, before settling in Rhodes where he founded a school. Among those he taught were Cicero (77 BC) and Pompey (66BC). The last years of his life were spent in Rome.

An eclectic, widely read and systematic scholar, Posidonius has been compared by many historians to Democritus and Aristotle. He travelled extensively, and used his voyages to make a systematic study of the geography of numerous countries in both the East and the West. He travelled to North Africa, the Iberian Peninsula and the Balearic Islands, to the shores of the Atlantic, to Britain and Germany, to the lands bordering the Adriatic, to Sicily and Sardinia, and to France, particularly the area around Massalia.

His influence on philosophical thinking remained very powerful until the Middle Ages. Posidonius is considered a true representative of the spirit of the Hellenistic period. He is cited by Strabo and Suidas.


Work
His work included:

A compendium of geographical and anthropological information on many different countries.

New calculations of the dimensions of the earth, and a new map of the world.

Construction of a globe.

Distribution of the terrestrial and celestial spheres into 5 zones.

Observations on earthquakes and volcanoes. Record of the eruptions of the volcanoes in the Aeolian islands, north of Sicily.

First interpretation of the tides as connected with the action of the sun and the moon.

- The Posidonius Equator: Posidonius fixed as the Equator of the earth the parallel passing through Rhodes, and calculated its length at 180,000 stades (32,400 km). The true value is 32,000 km.

His writings, of which all but a few fragments are lost, are:

"On the world"

"On the ocean"

"Periplus or Periegesis"

"On meteorology" (Elements of Meteorology).

"On meteors"

"Histories": History of the period 144 - 82 BC, in 52 books. Continuation of the History of Polybius.

"Commentary on the Timaeaus"

"The Art of War"