How is the universe organized? There are many theories. The Geocentric Model states the Earth is at the center of the universe. This was one of the older theories and made sense to people because people did not feel like they were on a moving object and they saw objects (sun, stars, moon) move across the sky. In this theory all objects move at the same speed. A problem with the geographic model was the observation that objects were in different locations in the sky on different days.
The Heliocentric Model states the sun is at the center of the universe. The planets and other objects revolve around the sun. This model was proposed by Nicolaus Copernicus. Galileo Galilei, Johannes Kepler, and Isaac Newton supported this model. Galileo used his telescope to support the model. Kepler used math to calculate the orbits of planets. Newton's laws of motion and gravity explained orbits. Scientific and mathematical evidence supported the heliocentric model.