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The Ptolemaic model placed Earth at the center of the universe and used complex superpositions of circles to describe planetary motion. What key limitation of this model made the Copernican model preferable?
AThe Ptolemaic model could never grow more accurate with more circles
BThe Ptolemaic model was purely descriptive, with no cause given
CThe Ptolemaic model required no data collection whatsoever
DThe Ptolemaic model placed the Sun at the center instead of Earth
Answer & Solution
Correct answer: B. The Ptolemaic model was purely descriptive, with no cause given
1. The Ptolemaic model could in fact be made progressively more accurate by adding more circles to the description.
2. Its real limitation was that it remained purely descriptive, giving a list of rules for each heavenly body's motion without any underlying cause.
3. The Copernican model, with the Sun at the center, could instead be explained by a small number of physical laws, including Newton's universal law of gravitation.
4. The Ptolemaic model still required careful astronomical data collection to fit its circles, and it placed Earth, not the Sun, at the center, which is exactly what the Copernican model changed.
_Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section 6.6 Satellites and Kepler's Laws: An Argument for Simplicity_
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