In 140 . a Greek astronomer named Ptolemy wrote that the Earth was the center of the universe. He thought all the stars, the Sun, and the Moon revolved around it. This made sense because that is how things looked in the sky from Earth. We call Ptolemy’s theory the geocentric view. It is derived from geo (Earth) and centric (center). Astronomers believed the geocentric view for 1,500 years until 1543. The Heliocentric View About 500 years ago, Copernicus found that the Earth and other planets revolve around the Sun. His theory was published in1543. We call Copernicus’s theory the heliocentric view because helios means sun. Astronomers still base their understanding of the Solar System on Copernicus’s heliocentric view
