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Home , Aristarchus of Samos, Equant

Aristarchus of - a student of Straton

“[Aristarchus’s] hypotheses are that the fixed stars and the remain unmoved, that the revolves about the Sun on the circumference of a circle, the Sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same center as the Sun, is so great that the circle in which he supposes the Earth to revolve bears such a proportion to the distance of the fixed stars as the centre of the sphere bears to its surface.” -- in (310 BC -- 220 BC) “the ” the last part makes no sense... Aristarchus of Samos

“Only do not, my good fellow, enter an action against me for impiety in the style of , who thought it was the duty of the to indict Aristarchus of Samos on the charge of impiety for putting in motion the Hearth of the , this being the effect of his attempt to save the phenomena by supposing the heaven to remain at rest and the Earth to revolve in an Aristarchus of Samos oblique circle, while it rotates, at the same time, (310 BC -- 220 BC) about its axis.” -- “the mathematician” Aristarchus of Samos: measuring the

Aristarchus of Samos (310 BC -- 220 BC) “the mathematician”

5 ingredients: (i) size of Earth’s shadow at the (ii) subtended by the sun (iii) angle subtended by the Earth (iv) angle between sun and moon when half full give: (i) distance to the moon (ii) distance to the sun (iii) size of the moon (iv) size of the sun

Almagest = al majisti (arabic) = the megiste (greek) = the greatest Claudius Ptolemy (90 -- 168)

In use until the 1600s

The , Latin edition, 1515 Ptolemy

Claudius Ptolemy (90 -- 168) Ptolemy

[from an actual University course web site]

Why was the Ptolemaic model unable to correctly explain retrograde motion?

The Ptolemaic model placed a stationary Earth at the center of the universe. Since the Earth did not move in the model, it assumed that retrograde motion was real instead of an optical illusion created by Earth’s motion. This meant that the model’s planetary motions were wrong. The result was that the model could not accurately predict the location of the in the sky, because the planets’ motion was incorrectly described.

Claudius Ptolemy (90 -- 168) bizarrely circular and nonsensical! ’s Academy

A grove sacred to Akademos, an Athenian hero. Justinian was intent on restoring the ancient Roman Empire. He Shut by Justinian I in 529. thought it should be unified by one religion The Hagia Sophia and ruthlessly persecuted all non- Chalcedonian-christians. quiz

The Greeks had the ability to The Academy was shut by Justinian measure the size of the sun because he * disliked the Greeks * true true * false * was attempting to unify the empire * was suppressing non-Catholic religions

* was suppressing a rebellion (b) or (c)

Greek philosophers had no political hylomorphism underpins troubles developing their theories * the immaculate conception

* true false * transubstantiation * false * dyophysitetism transubstantiation * Nestorianism quiz

Ptolemy’s book was called ’s influence * the System of the World * was minimal * the Principles of Philosophy * lasted for hundreds of years * the Almagest * lasted for thousands of years the Almagest * the Thinker thousands of years

comets exist in decay exists in sublunar realm

* the sublunar realm sublunar realm * the sublunar realm * the supralunar realm * the supralunar realm * the heavenly sphere * the heavenly sphere Review

- Thales - Empedocles - philosophers tended to be wealthy - - Greek philosophy built on the Egyptians and - Eudoxus Babylonians - Plato - centers of philosophy (and ) follow - Aristotle economic powers - Aristarchus - Ptolemy Review

- teleology - the four elements - atoms - the fifth element - the void - retrograde motion - hylozoism - cosmogony - Nous - matter and form (hylomorphism) - Love and Strife - Demiurge - - epicycle - deferent - Almagest