134 Flashcards
What were the two competing models of the universe developed by the Greeks?
Geocentric model and heliocentric model
The geocentric model assumes Earth is the center, while the heliocentric model considers the sun as the center.
Who created the first model of a geocentric universe?
Eudoxus
Eudoxus lived from 480 to 355 BCE.
What is the concept of homocentric in Eudoxus’s model?
Celestial spheres share one common center, Earth
This model features 27 spheres for various celestial bodies.
How many spheres are included in Eudoxus’s model and what do they represent?
27 spheres: one for fixed stars, three for the sun, three for the moon, and four for each of the five planets
The five planets are Mercury, Mars, Venus, Jupiter, and Saturn.
What was Aristotle’s main critique of Eudoxus’s model?
Eudoxus did not explain how the planets moved and interacted
Aristotle sought to address these issues in his own model.
What did Callippus add to Eudoxus’s model?
Two spheres for the moon and sun, one for Venus, Mercury, and Mars
Callippus’s model retained the number of spheres for Jupiter, Saturn, and fixed stars.
How many spheres are in Callippus’s model?
34 spheres
This includes the modifications made to Eudoxus’s original model.
How many total spheres does the Aristotelian model have?
56 spheres
This model includes additional spheres for the sun, Venus, Mercury, and Mars.
What concept did Aristotle propose to explain the motion of the planets?
The concept of the Prime Mover
The Prime Mover drives the motion of the celestial bodies.
Fill in the blank: Eudoxus’s model features _____ spheres.
27
These spheres include those for fixed stars, the sun, the moon, and the five planets.
True or False: The heliocentric model was supported by Eudoxus.
False
Eudoxus supported the geocentric model.
