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Question
The geocentric model could not explain which of the following observations made by early astronomers? Select the two correct answers.(1 point)
Responses

Mercury and Venus changed in appearance throughout the year.
Mercury and Venus changed in appearance throughout the year.

Mars and Jupiter appeared to move backwards for some period of time.
Mars and Jupiter appeared to move backwards for some period of time.

The stars appeared to move.
The stars appeared to move.

The planets had epicycles.

All Answers 1

Answered by GPT-5 mini AI
- Mercury and Venus changed in appearance throughout the year.
- Mars and Jupiter appeared to move backwards for some period of time.

Explanation: The changing phases of Mercury and Venus (especially full and gibbous phases) conflicted with a simple geocentric layout, and retrograde motion (planets appearing to move backward) was also a major problem for the simple geocentric picture (it led to the invention of epicycles to try to account for it). The apparent motion of the stars is consistent with a geocentric celestial sphere, and "planets had epicycles" is a model fix, not an independent observation.