Venus shows changes in angular size and also shows phases similar to the phases of the Moon. According to Galileo, who first saw the phases, these observations showed that Venus
A) orbits Earth in an elliptical orbit.
B) moves in epicycles.
C) does not rotate on its axis.
D) orbits the Sun.

Question

Quizplus · Accepted Answer

The observation of phases of Venus, similar to those of the Moon, and changes in its angular size can only be explained if Venus orbits the Sun. This observation by Galileo was one of the key pieces of evidence supporting the heliocentric model of the solar system, where planets orbit the Sun, rather than the geocentric model, where everything was thought to orbit Earth.

Venus Shows Changes in Angular Size and Also Shows Phases