The book entitled "Assayer" published in 1623 was a controversial text about the theory of comets between Galileo and his opponent Horatio Grassi, the Jesuit mathematician. Galileo was an author of the original but false optical theory of comets while Grassi proposed a supra-lunar origin of comets supporting Tycho's opinion on comets and their motion. Unfortunately, Grassi's theory was based on a misunderstanding of how the telescope actually works., Vladimír Štefl., and Obsahuje bibliografii
The article outlines the book culture of the Rudolphine period on the examples of several works by Tycho Brahe (Instruments of the Renewed Astronomy), Johannes Kepler (Somnium: The Dream, or Posthumous Work on Lunar Astronomy; Conversation with the Starry Messenger) and Galileo Galilei (The Starry Messenger). It is based on both research outcomes that have already been published and those that are being prepared for printing. and Alena Hadravová.