135 Flashcards
What model did Claudius Ptolemy propose around 140 CE?
Ptolemaic Model
The Ptolemaic model is a refinement of the geocentric model.
What does the term ‘deferent’ refer to in the Ptolemaic model?
A circular path in which the planet moves around Earth
The deferent is a key component of the Ptolemaic model.
What does the term ‘epicycle’ refer to in the Ptolemaic model?
A smaller circle along which a planet moves
Epicycles are used to explain the complex motion of planets.
What concept did Ptolemy adopt regarding the motion of planets?
Uniform circular motion
This concept underlies the Ptolemaic model’s explanation of planetary motion.
What were the three concepts that influenced Ptolemy’s ideas on planetary motion?
- Epicycle of the planet
- Eccentric position of the observer
- Equant point
These concepts contributed to the development of the Ptolemaic model.
What is the equant in the context of the Ptolemaic model?
The point with the same distance as that of Earth to the center
The equant helps explain the apparent motion of planets.
How long did the Ptolemaic model last?
About 14 centuries
The model was predominant until the Copernican revolution.
Who hypothesized that the sun is at the center of the universe?
Aristarchus of Samos
Aristarchus proposed a heliocentric model centuries before Copernicus.
What did Aristarchus claim about the size of the sun compared to Earth?
The sun is much larger than Earth
This claim was based on his analysis of Earth’s shadow during a lunar eclipse.
What work did Aristarchus write regarding celestial sizes and distances?
On the Sizes and Distances of the Sun and the Moon
This work contains his arguments about the relative sizes of celestial bodies.
True or False: Ptolemy’s findings were entirely original and not influenced by earlier philosophers.
False
Most of Ptolemy’s findings were rooted in Aristotle’s earlier work.
Fill in the blank: The Ptolemaic model grew in influence because it summarized the theory of _______.
planetary motion
The model was significant for its comprehensive explanation of celestial mechanics.
What did Aristarchus believe about the size of the universe?
It is much wider and larger than previously believed
This was a radical idea for his time.
