In about 100 A.D. before the scientific revolution, Ptolemy came up with the geocentric theory. The geocentric theory stated that the earth was the center of the universe and that the sun and planets revolved around it. At the start of the scientific revolution, Copernicus, Kepler, and Galileo all contributed to the challenging of Ptolemy's theory. In the early 1500's Copernicus theory developed to be almost the exact opposite of Ptolemy's. Copernicus believed that the sun was the center of the universe and that the earth and all the other planets revolved around it. Because Copernicus's idea contradicted the church and the senses, few people believed it.
In the late 1500's and early 1600's, Johannes Kepler used mathematics to test Copernicus's theory. After many calculations and slight changes to Copernicus's ideas, he decided that the heliocentric theory could be mathematically supported. In 1632, Galileo Galilei published his proof to the heliocentric theory in Dialogue on the Two Great Systems if the World. Galileo was the first to use a telescope to look at stars and planets. Using the telescope, Galileo was able to prove that Earth rotated on its axis, and that Jupiter's moons revolved around Jupiter, proving that not everything revolves around the earth. When Galileo published his ideas, it caused a major chaos. Because his work contradicted scripture, the church was very disapproving. In 1663, Galileo was sent to Rome to recant his beliefs. Galileo did as he was told, but it was too late.