• DOI:10.1111/j.1749-6632.1987.tb37224.x
• Corpus ID: 222087224

The Heliocentric System in Greek, Persian and Hindu Astronomy

@article{vanderWaerden1987TheHS,
  title={The Heliocentric System in Greek, Persian and Hindu Astronomy},
  author={B. L. van der Waerden},
  journal={Annals of the New York Academy of Sciences},
  year={1987},
  volume={500}
}

• B. L. van der Waerden
• Published 1 June 1987
• Physics
• Annals of the New York Academy of Sciences

N THE YEARS 295-283 B.c., Timocharis observed positions of the moon and I of Venus with respect to the fixed stars.’ About 280 B.c., Aristarchos of Samos proposed the heliocentric hypothesis.2 At about the same time, a man named Dionysios established an astronomical calendar based on the assumption of a tropical year of 365 y4 days3 An anonymous observer used this calendar to date his observations of Mercury, Mars, and Jupiter made in the years 270-239 B.c .~ The observations of Timocharis and those of the unknown observer complement each other nicely: Ptolemy was able to use the observations of Timocharis for the moon and Venus, and the anonymous observations for Mercury, Mars, and Jupiter. In another case too we have two series of observations that complement each other. Timocharis observed the declination of twelve fixed stars, and Aristyllos observed the declination of six more stars.5 From independent investigations by Rawlins and Maeyama6 we may conclude that the observations of Aristyllos were made with great accuracy between 280 and 240 B.C. We may suppose that Timocharis observed his declinations between (say) 290 and 270 B.c., and that Aristyllos continued the program of Timocharis. It seems that here a team was at work, consisting of three observers and a calendar maker (or perhaps of three observers only). What was the purpose of their teamwork? In all cases in which we know the whole story, the purpose of astronomical observations is always: to determine the constants of an astronomical system, with the ultimate aim of computing tables based on that system. For instance, Ptolemy used the observations of Timocharis and Aristyllos and of our anonymous observer in order to determine the constants in his theory, and next he composed ”handy tables” for the use of astrologers. The same order of events can be observed in Babylonia, in India, in the Islamic realm, and in Western Europe. So it is not unreasonable to suppose that the purpose of the observations made in Alexandria between 295 and 239 B.C. was: to de-