The Sphere has the distinction of being one of the most successful scientific texts ever written. Within a few decades of its composition in 1472, it became the most popular and widely used astronomy textbook in Europe, serving as the basis for introductory astronomy lectures at universities from the mid-thirteenth to the end of the seventeenth century. As astronomy was part of the basic arts curriculum that all students had to complete before advancing to any of the higher faculties, a very high percentage of university-educated men would have been exposed to this text. According to the most recent estimates, there were over 200 different editions of the Sphere printed between 1472 and 1673. In part 4 he discusses the Stella Nova discovered by Thyco Brahe in 1572