Among the various historical studies on the topic of “Scientific Revolution,” there is not sufficient consideration of the deep cognitive changes generated by scientific measurements, although there is usually an emphasis on the theory change.1 A well-known case of theory change is Nicholas Copernicus’s (1473-1543) planetary theory, which was stated as an alternative explanation to Claudius Ptolemy’s (ca. AD 100-ca. AD 170). Developing a planetary theory supposing that the earth rotates around a motionless sun was not only a simpler theory but also a stronger explanatory theory. However, an interesting methodological and cognitive issue was that Copernicus’s astronomical measurements and data were not notably different from Ptolemy’s. In fact, in many cases, Copernican data concerning key astronomical parameters was the same as in Ptolemy’s theory. Therefore, in this instance, we have two inconsistent theories concerning planetary motion derived from nearly the same measurements.