The greatest inaccuracy in Copernicus's theory of the solar system was that he
A) placed the planets in circular orbits.
B) placed the planets on epicycles,the centers of which followed orbits around Earth.
C) did not allow for retrograde motion.
D) assumed that the planets move in elliptical orbits with constant speeds rather than variable speeds.

Question

Quizplus · Accepted Answer

Copernicus correctly placed the planets in orbits around the Sun, but he assumed these orbits were circular. The more accurate model, proposed later by Johannes Kepler, showed that the orbits are elliptical, not circular.

The Greatest Inaccuracy in Copernicus's Theory of the Solar System