Status of the Copernican theory before Kepler, Galileo, and Newton

The most obvious evidence supporting the Copernican theory emerged during a period of 300 years following the publication of De Revolutionibus by Copernicus in 1543. In this paper a comparison is made between the geo‐centric and helio‐centric theories on the basis of astronomical merit and observational evidence available in 1543. The Copernican theory is not superior on the basis of calculational accuracy, but does possess greater unity and is simpler in the sense that ad‐hoc assumptions required by the geo‐centric theory are not required by the Copernican theory. The Copernican theory, however, requires an ad‐hoc assertion about the size of the universe in order to explain the absence of observed stellar parallax.