De revolutionibus orbium coelestium
This was an alternative model of the universe to Ptolemy's Earth-centered system, which had been accepted since ancient times.
Copernicus had worked his ideas out many years before, but was afraid to publish, fearing the anger of the Roman Catholic Church. Finally, the book was published just before he died.
In its standard English edition, the book contains 330 folio pages, 100 pages of tables, and over 20,000 tabulated numbers.
De revolutionibus is divided into six "books" (sections or parts):
- Book I is a general vision of the heliocentric theory, and a summarized exposition of his cosmology.
- Book II is mainly theoretical and describes the principles of spherical astronomy and a list of stars, as a basis for the arguments developed in the following books.
- Book III describes the apparent movements of the Sun and related phenomena.
- Book IV is a similar description of the Moon and its orbital movements.
- Books V and VI are the exposition of the new system. They explain how to calculate the positions of astronomical objects based on the heliocentric model.
This book is often referred to as the start of modern science.