thought, which may have initially inspired his vision of a heliocentric universe. Copernican Revolution Commonly regarded as the foundation of modern astronomy, the common universal view of the cosmos shifted as Nicolaus Copernicus positioned the Sun as the center of the Universe. Early beliefs Prior to the Copernican Revolution, the Ptolemaic system, also known as the geocentric model, was widely accepted. This put the Earth at the center of the universe, with the sun and other planets revolving around the earth in an epicyclic orbit. Aristotle's geocentric model was also broadly acknowledged, along with his claim that the planets rotated but did not orbit. The reasoning behind this was due to the belief that all objects outside of the lunar sphere were celestial bodies, and therefore could not change, as they were made of quintessence. There were notable critiques of this model prior to Copernicus. In the Islamic world, Ibn al-Haytham doubted Ptolemy's notion of the planetary orbits, and Muhammad al-Battani recalculated the parameters. However, both still agreed with the geocentric model. One of the first known astronomers that supported the Heliocentric theory was Aristarchus of Samos. After observing a lunar eclipse, he came to the conclusion that the sun was farther away from earth than the moon and that the sun was much larger than Earth. He also claimed the sun was a star. While Aristarchus was later an influence on Copernicus and his groundbreaking work, prior to the 17th century Aristarchus' findings were obstructed by the more established theories of Ptolemy and Aristotle. Copernican theory Astronomer and mathematician Nicolaus Copernicus was appointed by the Catholic Church as an official, as his uncle was a bishop in the church. He used his income to further his studies, eventually studying at the University of Bologna in Italy. Copernicus began doubting the knowledge of natural philosophers and their beliefs, claiming that geometrical astronomy instead would result in the true reality of the cosmos. His manuscript, De revolutionibus, pioneered ideas that would change the course of how both the cosmos and astrology were viewed. Most notably, Copernicus claimed that the sun was the stationary center of the universe. His work also included calculations on the motions of the moon, and the motions in latitude and longitude of the planets, all which orbit the sun. Copernicus' work was not immediately published as it disagreed with Biblical teachings, and he feared his work would