Then he saw four moons of Jupiter rotating around Jupiter. While these discoveries did not prove Copernicus' theory, they provided a framework for thinking about the universe in new terms. He thought that perhaps the Earth's moon also revolves around the planet while the Earth orbits around the sun. Another observation of his was that Venus itself had phases like the Moon did, even though the planet always appeared as a bright spot from Earth. (Strange 23-9). Furthermore, in the “Dialogue Concerning the Two Chief World Systems,” astronomer Galileo Galilei did not prove that the earth revolves around the sun or rotates on its axis, but he did prove that Ptolemy was wrong about the arrangement of the planets (Gingerich 141) . From then on, Galileo wanted the Earth to move, not the Sun, and he got his answer by observing ocean tides. “Galileo explains how the observed motion of the sea is a direct consequence of the two absolute motions of the earth in space: its axial rotation and its orbital motion around the sun” (Naylor 11-5). In short, it argues that the movement of the earth causes the movement of tidal waves. The book was popular in its time before the Roman Catholic Church banned it. The church had a problem with supporting Galileo