It was once believed that all of the bodies of the solar system were perfect spheres with absolutely nothing on their surfaces. How did Galileo disprove this notion in the early 1600s?
A.
He used a gyroscope to measure the gravity of Jupiter.

B.
He used a rocket to measure the width of Earth's atmosphere.

C.
He used a spectroscope to observe the light from the Sun.

D.
He used a telescope to observe mountains on the Moon.