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Aristarchus of Samos, a prominent Greek astronomer and mathematician from the 3rd century BCE renowned for his heliocentric model of the Solar System. This revolutionary theory placed the Sun, not Earth, at the center of the universe, contradicting prevailing beliefs at the time. Despite its scientific significance, Aristarchus's model wasn't widely accepted until the 16th century when Nicolaus Copernicus revived and further developed it.