Galileo's observations of a complete set of phases of Venus proved
A) that Venus orbited the sun.
B) that Earth orbited the sun.
C) that all of the planets orbited the sun.
D) that the moon orbited Earth.
E) that Venus had an atmosphere.

Question

Quizplus · Accepted Answer

While Galileo's observations helped support the idea that all planets orbited the sun, his observations of Venus specifically provided evidence that it orbited the sun rather than the Earth. By observing a complete set of phases of Venus, Galileo was able to show that Venus was sometimes between the Earth and the sun (as evidenced by its phase being a thin crescent) and sometimes on the far side of the sun (as evidenced by its phase being nearly full). This could only happen if Venus was orbiting the sun rather than the Earth.

Galileo's Observations of a Complete Set of Phases of Venus