Question

Copernicus's heliocentric model and Ptolemy's geocentric model were each developed to provide a description of the solar system. Both models had advantages that made each an acceptable explanation for motions in the solar system during their time.

Sort each statement according to whether it is an advantage of the heliocentric model, the geocentric model, or both.

Drag the appropriate items to their respective bins.

• Planetary orbits and motions based on Greek ideologies of perfect form and motion
• Predicted planetary positions accurately over relatively short time periods
• Explained planetary motions and brightness changes most simply
• Rooted in widely accepted religious beliefs regarding Earth's place in the universe

• Heliocentric:

• Geocentric:

• Both geocentric and heliocentric:

Answer 1

Satement 1: Planetary orbits and motions based on Greek ideologies of perfect form and motion

Bin: Both geocentric and heliocentric

Explaination: Greeks believed that the planets moved in perfect circular orbits and had a fixed period of motion. Both the geocentric model and the heliocentric model had circular orbits with fixed periods.

Statement2: Predicted planetary positions accurately over relatively short time periods

Bin: Both geocentric and heliocentric

Explaination: You would think that the heliocentric model could give planetary positions more accurately than the geocentric model but in reality, the heliocentric model was no more accurate than the geocentric model because it still used circular orbits. Both the gecentric model and the heliocentric model predicted planetary positions accurately over relatively short time periods.

Statement3: Explained planetary motions and brightness changes most simply

Bin: Heliocentric

Explaination: The geocentric model could not explain brightness changes because in the geocentric model, a planet was always the same distance from earth (circular orbit around earth). Also, the geocentric model had to rely on epicycles to account for the retrograde motion of some planets like Mars. The heliocntric model explained both the brightness changes and retrograde motion very simply. Brightness changes occur because a planet is not always the same distance from the earth. Planets move with different speed around the sun and retrograde motion is the apparent motion of the planet when the earth is passing by it.

Statement4: Rooted in widely accepted religious beliefs regarding Earth's place in the universe

Bin: Geocentric

Explaination: The widely accepted religious belief about the earth's place in the universe was that the earth was at the center of the universe and eveything including the planets and the distant stars revolved around the earth. Geocentric model was based on this belief.

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