Most people in Galileo's time believed that the Earth was the center of the universe and that the Sun and planets revolved around it. The Catholic Church, which was very powerful and influential in Galileo's day, strongly supported the theory of a geocentric, or Earth-centered, universe.
They thought that the solar system we live in was the whole universe. So when they referred to the universe, they really meant only our solar system. Galileo did not agree that our universe is geocentric, or that everything revolves around Earth.
