Caption: Aristarchos of Samos (c.310--c.230 BCE), the dark star of ancient Greek astronomy.

Features:

1. Not much is known about Aristarchos, but he is the first person in recorded history to propose heliocentrism: i.e., the heliocentric solar system.

   By the way, heliocentrism, of course, implies the daily axial rotation of the Earth---you CANNOT have one without the other in any reasonable theory.

2. Pretty much all that is known about Aristarchos is detailed in Wall, B. E. 1975, "Anatomy of a Precursor: The Historiography of Aristarchos of Samos", Studies in History and Philosophy of Science 6, 201.

3. We only know Aristarchos proposed heliocentrism from a few comments in surviving ancient writings.

4. The only surviving work attributed to Aristarchos, On the Sizes and Distances of the Sun and Moon, is an important theoretical work on astronomical measurement, but is based on a geocentric Solar System. His methods did NOT work in practice. His geometry was strong, his instruments were weak. Ironically, On the Sizes and Distances of the Sun and Moon, takes a geocentric perspective.

5. The comments on Aristarchos' heliocentrism do NOT tell us Aristarchos' reasons for proposing heliocentrism---why he thought heliocentrism was a good theory. It's reasonable to guess, these reasons were at least partly the same reasons that led Nicolaus Copernicus (1473--1543) to heliocentrism (see Copernicus file: venus_elongation.html) ∼ 18 centuries after Aristarchos. Aristarchos should really have explained his ideas in a book and made them an unignorable hypothesis. It might have saved humankind a lot of time.

6. Actually, Aristarchos may have written a book on his heliocentric model, but it has NOT survived if it existed. The "book" was mentioned by in a book attributed to Archimedes (c.287--c.212 BCE) called The Sand Reckoner. But the word "book" may be a mistranslation from the Greek word γραφη (graphai) which can be writing as in a book, but can also just mean drawing (see Wall, 1975, p. 203). It may be that a γραφη (graphai) of his heliocentric model was just shown in person by Aristarchos to Archimedes while the two were hobnobbing at Mousieon of Alexandria in Alexandria, Egypt.

7. Despite Aristarchos' priority with the idea of heliocentrism, Copernicus is justly credited as the innovator since he presented a detailed argument that was somewhat convincing and was NOT ignorable.

   This is often the way in the history of science.

   The giver a convincing proof or argument gets more fame than the speculator---and this seems just.

8. The only other astronomer to adopt heliocentrism before Copernicus was Seleucus of Seleucia (fl. 150 BCE). Seleucus is said to have given an argument for heliocentrism---but what that argument was has NOT survived.

9. Aristarchos and Seleucus are precursors of a discovery.

   A precursor in history of science jargon is a person who discovers something, but fails to make the world appreciate it's value---a prophet without honor in his time.

10. Actually, Aristarchos had his own partial precursors: ancient Greek astronomers who thought the Earth's motion was possible. Philolaus (c.470--c.385 BCE) had moving Earth in his Philolaic system (see Ancient Astronomy file: philolaus_cosmos.html), but this Solar System model is neither heliocentric nor geocentric and may NEVER have been considered as realistic Solar System model. Hicetas (c.400--c.335 BCE) and Heraclides Ponticus (c.390--c.310 BCE) both suggested daily rotation of the Earth on the Earth's axis as an explanation of the diurnal rotation of the celestial sphere. There has been a longstanding idea that Heraclides Ponticus (c.390--c.310 BCE) also suggested that Mercury and Venus orbit the Sun. But this is a modern idea now shown NOT to be supported by ancient texts (see Wikipedia: Heraclides Ponticus: Work; Eastwood 1992). So Aristarchos remains the first proposer of heliocentrism in recorded history.