Aristarchus of Samos (l. c. 310 - c. 230 BCE) was a Greek astronomer who first proposed a heliocentric model of the universe in which the sun, not the earth, was at the center. Although his theory was noted by other thinkers of his time, it was rejected as implausible, and the geocentric model was retained for 1,700 years afterward.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Aristarchus_of_Samos/.