Aristarchus of Samos
- a student of Straton
Aristarchus of Samos
“[Aristarchus’s] hypotheses are that the fixed stars and
the Sun remain unmoved, that the Earth 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.” -- Archimedes in The Sand Reckoner
(310 BC -- 220 BC)
“the mathematician”
the last part makes no
sense...
Aristarchus of Samos
Aristarchus of Samos
(310 BC -- 220 BC)
“the mathematician”
“Only do not, my good fellow, enter an action
against me for impiety in the style of Cleanthes,
who thought it was the duty of the Greeks to
indict Aristarchus of Samos on the charge of
impiety for putting in motion the Hearth of the
Universe, 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
oblique circle, while it rotates, at the same time,
about its axis.” -- Plutarch
Aristarchus of Samos:
measuring the Solar System
Aristarchus of Samos
(310 BC -- 220 BC)
“the mathematician”
5 ingredients:
(i) size of Earth’s shadow at the moon
(ii) angle subtended by the sun
(iii) angle subtended by the Earth
(iv) angle bet ween 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
Ptolemy
Almagest = al majisti
(arabic) = the megiste
(greek) = the greatest
Claudius Ptolemy
(90 -- 168)
In use until the 1600s
The Almagest , 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 planets in the sky, because the planets’ motion was
incorrectly described.
Claudius Ptolemy
(90 -- 168)
bizarrely circular and
nonsensical!
Plato’s Academy
A grove sacred to
Akademos, an Athenian
hero.
Shut by Justinian I in 529.
Justinian was intent on
restoring the ancient
Roman Empire. He
thought it should be
unified by one religion
and ruthlessly
persecuted all nonChalcedonian-christians.
The Hagia Sophia
quiz
The Greeks had the ability to
measure the size of the sun
* true
* false
true
Greek philosophers had no political
troubles developing their theories
* true
* false
false
The Academy was shut by Justinian
because he
* disliked the Greeks
* was attempting to unify the empire
* was suppressing non-Catholic religions
* was suppressing a rebellion (b) or (c)
hylomorphism underpins
* the immaculate conception
* transubstantiation
* dyophysitetism
transubstantiation
* Nestorianism
quiz
Ptolemy’s book was called
Aristotle’s influence
* the System of the World
* the Principles of Philosophy
* the Almagest
the Almagest
* the Thinker
thousands of years
decay exists in
comets exist in
* the sublunar realm
* the supralunar realm
* the heavenly sphere
* was minimal
* lasted for hundreds of years
* lasted for thousands of years
sublunar realm
sublunar realm
* the sublunar realm
* the supralunar realm
* the heavenly sphere
Review
- Thales
- Empedocles
- philosophers tended to be wealthy
- Democritus
- Greek philosophy built on the Egyptians and
Babylonians
- Eudoxus
- centers of philosophy (and science) follow
economic powers
- Plato
- Aristotle
- 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
- equant
- epicycle
- deferent
- Almagest