Historically, most all believed the Earth was at the center of the Universe (geocentric) as Aristotle and Ptolemy had taught. But in the 3rd Century B.C., a greek by the name of Aristarchus of Samos proposed the opposite - the Sun at the center of the Universe (heliocentric) but this did not get much support. Then in the 16th Century A.D., a pole by the name of Nicholas Copernicus proved Aristarchus correct. A bit latter, Galileo, using a 'telescope' supported this discovery. Yet, Galileo was forced to recant all by the powerful RC Church.