Unit 5: Lesson 1: Early Astronomy Assessment Questions

What role did the telescope play in Galileo's contributions to science?

The telescope allowed Galileo to view the universe in a new way, leading to many discoveries on his part.

What major change did Copernicus make in the Ptolemaic system? Why was this change significant?

Copernicus placed the sun at the center of the solar system. This was a major break from the ancient idea that Earth lies at the center.

Compare and contrast the geocentric and heliocentric models of the universe.

In the geocentric model, the sun and planets revolve around Earth. In the heliocentric model, Earth and the other planets revolve around the sun.

What geometric arrangements did Ptolemy use to explain retrograde motion?

Ptolemy said that planets moved on small circles called epicycles, which in turn moved along their orbits around Earth.

What produces the retrograde motion of Mars?

Retrograde motion occurs when Earth, which travels faster than Mars, passes Mars. This makes Mars appear to go westward.

Summarize Kepler's three laws of planetary motion.

The path of a planet around the sun is an ellipse. Each planet revolves so that an imaginary line connecting it to the sun sweeps over equal areas at equal time intervals. The squares of the orbital periods of the planets to the cubes of their average distances from the sun.