Copernican revolution (book)

The Copernican Revolution: Planetary Astronomy in the Development of Western Thought is a 1957 book by Thomas S. Kuhn (Harvard University Press).

The book describes the ways Western Civilization looked at the solar system throughout history. It treats Copernicus' innovation—the Sun is in the center of the system—as the pivotal point in the development of this view.

Chapter 1 explains a good deal of astronomical theory. It treats the apparent motion of the Sun as seen from Earth and introduces concepts as winter/summer solstice and vernal/autumnal equinox. It explains the ancient Two-Sphere Universe (a term coined by Kuhn), a tiny spherical Earth at the geometric center of the large rotating sphere of the stars.

Chapter 2 deals with the planets (derived from the Greek word for "wanderer"). For the Greek and their successors the Sun was one of the seven planets (Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn). The book details how the retrograde motion of the planets is explained by epicycles, small circles that rotate uniformly about a point on the circumference of a second rotating circle, the deferent. This theory culminated in the writing of the Almagest by Ptolemy.

Chapter 3 gives an account of Aristotelian cosmology and world view. The universe is bounded by the spheres of the stars and its interior is filled with aether. Further Aristotle believed that there were fifty-five crystalline shells and that these shells embodied a mathematical system of seven homocentric spheres carrying the planets.