Heraclides Ponticus (Ancient Greek: Ἡρακλείδης ὁ Ποντικός; c. 390 BC – c. 310 BC), also known as Herakleides and Heraklides of Pontus, was a Greek philosopher and astronomer who lived and died at Heraclea Pontica, now Karadeniz Ereğli, Turkey. He is best remembered for proposing that the earth rotates on its axis, from west to east, once every 24 hours. He is also frequently hailed as the originator of the heliocentric theory, although this is doubted.
Heraclides' father was Euthyphron, a wealthy nobleman who sent him to study at the Platonic Academy in Athens under its founder Plato and under his successor Speusippus. According to Suda, Plato, on his departure for Sicily in 361/360 BC, left the Academy in the charge of Heraclides. Heraclides was nearly elected successor to Speusippus as head of the academy in 339/338 BC, but narrowly lost to Xenocrates.
Like the Pythagoreans Hicetas and Ecphantus, Heraclides proposed that the apparent daily motion of the stars was created by the rotation of the Earth on its axis once a day. This view contradicted the accepted Aristotelian model of the universe, which said that the earth was fixed and that the stars and planets in their respective spheres might also be fixed. Simplicius says that Heraclides proposed that the irregular movements of the planets can be explained if the earth moves while the sun stays still. 
Although some historians have proposed that Heraclides taught that Venus and Mercury revolve around the Sun, a detailed investigation of the sources has shown that "nowhere in the ancient literature mentioning Heraclides of Pontus is there a clear reference for his support for any kind of heliocentrical planetary position."
A punning on his name, dubbing him Heraclides "Pompicus," suggests he may have been a rather vain and pompous man and the target of much ridicule. According to Diogenes Laertius, he forged plays under the name of Thespis, and according to the same author, this time drawing from a different source, Dionysius the Deserter composed plays and forged them under the name of Sophocles. Heraclides was deceived by this easily and cited from them as the words of Aeschylus and Sophocles. However, Heraclides seems to have been a versatile and prolific writer on philosophy, mathematics, music, grammar, physics, history and rhetoric, notwithstanding doubts about attribution of many of the works. It appears that he composed various works in dialogue form.
Heraclides also seems to have had an interest in the occult. In particular he focused on explaining trances, visions and prophecies in terms of the retribution of the gods, and reincarnation.
A quote of Heraclides, of particular significance to historians, is his statement that fourth century B.C. Rome was a Greek city.
- Tiziano Dorandi, Chapter 2: Chronology, in Algra et al. (1999) The Cambridge History of Hellenistic Philosophy, page 48. Cambridge.
- "Heraklides of Ponticus," The Hutchinson Dictionary of Scientific Biography
- Gottschalk, H. B. (1980). Heraclides of Pontus. Clarendon Press. p. 2. ISBN 0-19-814021-5.
- Guthrie, W. K. C. (1986). A History of Greek Philosophy: Volume 5, The Later Plato and the Academy (Later Plato & the Academy). Cambridge University Press. p. 470. ISBN 0-521-31102-0.
- Simplicius On Aristotle's Physics 2, tr. Barries Fleet (Ithaca: Cornell University Press), 48.
- Thomas L. Heath, A History of Greek Mathematics: From Thales to Euclid, (Oxford: Clarendon Press, 1921), pp. 312, 316-7.
- Bruce S. Eastwood, "Heraclides and Heliocentrism: Texts, Diagrams, and Interpretations," Journal for the History of Astronomy, 23(1992): 233-260, page 256.
- Davidson, Martin P. (2007). The Stars And The Mind. Fabri Press. p. 45. ISBN 1-4067-7147-3.
- Diogenes Laertius, V, Heraclides, 92:"Moreover, Dionysius, called the Deserter, or as some say Spentharus, wrote a tragedy called Parthenopaeus, and forged the name of Sophocles to it. And Heraclides was so much deceived that he took some passages out of one of his works, and cited them as the words of Sophocles; and Dionysius, when he perceived it, gave him notice of the real truth; and as he would not believe it, and denied it, he sent him word to examine the first letters of the first verses of the book, and they formed the name of Panculus, who was a friend of Dionysius. And as Heraclides still refused to believe it, and said that it was possible that such a thing might happen by chance, Dionysius sent him back word once more, "You will find this passage too:
- An aged monkey is not easily caught;
- He's caught indeed, but only after a time."
- Diogenes Laërtius trans. C.D. Yonge (1853) "Lives of Eminent Philosophers"
- O. Voss (1896) De Heraclidis Pontici vita et scriptis
- Wehrli, F. (1969) Herakleides Pontikos. Die Schule des Aristoteles vol. 7, 2nd edn. Basel.
- Neugebauer, Otto (1969) . The Exact Sciences in Antiquity (2 ed.). Dover Publications. ISBN 978-0-486-22332-2.
- O. Neugebauer (1975) A History of Ancient Mathematical Astronomy
- Hans B. Gottschalk (1980) Heraclides of Pontus New York, Oxford University Press
- Bruce Eastwood, "Heraclides and Heliocentrism: Texts, Diagrams, and Interpretations." Journal for the History of Astronomy 23 (1992): 233-60.
- Heraclides of Pontus. Texts and translations, edited by Eckart Schütrumpf; translators Peter Stork, Jan van Ophuijsen, and Susan Prince, Piscataway, N.J., Transaction Publishers, 2008
- Heraclides of Pontus. Discussion, edited by William W. Fortenbaugh, Elizabeth Pender, New Brunswick, N.J. : Transaction Publishers, 2009
- O'Connor, John J.; Robertson, Edmund F., "Heraclides Ponticus", MacTutor History of Mathematics archive, University of St Andrews.
- Diogenes Laërtius, Life of Heraclides, translated by Robert Drew Hicks (1925).