On the Revolutions of the Heavenly SpheresNicolaus Copernicus
About On the Revolutions of the Heavenly Spheres
Copernicus published in 1543, the year of his death. Six books, modeled on the structure of Ptolemy's , propose that the Earth rotates daily on its axis and yearly about the Sun, which stands near the center of the planetary system.
Book I states the cosmology: the world is spherical, the Earth is a sphere that moves, and the order of the planets is Mercury, Venus, Earth with its Moon, Mars, Jupiter, and Saturn, under a sphere of fixed stars. Book II treats spherical astronomy and a star catalogue. Books III and IV model the Sun's apparent motion and the Moon. Books V and VI give the planetary theories and their latitudes. Copernicus still requires epicycles and uniform circular motion; the decisive shift is the transfer of the center from Earth to Sun.
An unauthorized preface by Andreas Osiander presented the system as a computational hypothesis. Kepler refined the orbits into ellipses. Galileo defended the motion of the Earth in the . Newton derived the whole from universal gravitation. The book forced every later cosmology to decide whether the Earth moves.