Seleukus of Seleukeia

FlourishedSeleukia, (Iraq), 150 BCE

Seleukus appears to have argued for an infinite heliocentric kosmos, and was the first to hypothesize a mechanism for the long-known lunar influence on the tides. The precise nature of his theory is hard to determine, because his own writings have not survived.

Seleukus was from the city of Seleukeia, on the Persian Gulf near the mouth of the Tigris and Euphrates rivers, and studied with Mesopotamian astronomers and astrologers. His apparent date is determined from the fact that he responded to Krates of Mallos (who was himself active in the decades around 165 BCE), and he must have preceded Hipparchus ’ Geography, composed in the decades around 140 BCE, which responds to his ideas.

Plutarch , in the Platonic Questions 8.1, records that Seleukos proclaimed what Aristarchus had only hypothesized, that the Earth rotated; since Aristarchus also hypothesized that the Earth orbited the Sun, it is usually assumed that Seleukus did so as well. One ancient...