Who wrote the unsigned preface to De revolutionibus that framed the model as a calculation tool?

Andreas Osiander wrote the unsigned preface to De revolutionibus that framed heliocentrism as a calculation tool.

Osiander was a German theologian and minister who supervised the printing of Nicolaus Copernicus’s De revolutionibus orbium coelestium in Nuremberg in 1543. Without Copernicus’s authorization, he added a preface suggesting that astronomical hypotheses need not describe physical reality; they could simply provide convenient calculations of celestial motions.

The preface helped make the controversial book more acceptable to readers who expected astronomy to conform to established philosophy and theology. It also softened Copernicus’s more realist presentation of a moving Earth and stationary Sun. Because the preface was unsigned, later readers initially attributed it to Copernicus.

The attribution was eventually clarified, and historians identify Osiander as its author. Johannes Petreius was the printer, while Erasmus Reinhold later used Copernican methods in his Prutenic Tables; neither wrote this famous anonymous disclaimer.