Aristarchus was an astronomer who taught that the sun was the center of the universe, with the Earth and other planets orbiting it.

This was a revolutionary idea for his time, as most people believed in the geocentric model, where the Earth was the center of the universe. While his heliocentric model was not widely accepted until much later with Copernicus, Aristarchus's work is significant for its early and bold challenge to the established view of the cosmos.