
Theological and philosophical foundation Īs he indicated in the title, Kepler thought he had revealed God’s geometrical plan for the universe. However, Kepler later rejected this formula because it was not precise enough. Kepler also found a formula relating the size of each planet's orbit to the length of its orbital period: from inner to outer planets, the ratio of increase in orbital period is twice the difference in orb radius. He attributed most of the variances to inaccuracies in measurement. By ordering the solids correctly- octahedron, icosahedron, dodecahedron, tetrahedron, and cube-Kepler found that the spheres correspond to the relative sizes of each planet's path around the Sun, generally varying from astronomical observations by less than 10%. He found that each of the five Platonic solids could be uniquely inscribed and circumscribed by spherical orbs nesting these solids, each encased in a sphere, within one another would produce six layers, corresponding to the six known planets- Mercury, Venus, Earth, Mars, Jupiter, and Saturn. After failing to find a unique arrangement of polygons that fit known astronomical observations (even with extra planets added to the system), Kepler began experimenting with 3-dimensional polyhedra. Kepler claimed to have had an epiphany on July 19, 1595, while teaching in Graz, demonstrating the periodic conjunction of Saturn and Jupiter in the zodiac: he realized that regular polygons bound one inscribed and one circumscribed circle at definite ratios, which, he reasoned, might be the geometrical basis of the universe. Johannes Kepler's first major astronomical work, Mysterium Cosmographicum ( The Cosmographic Mystery), was the second published defence of the Copernican system.

He wrote, "I believe it was by divine ordinance that I obtained by chance that which previously I could not reach by any pains." But after doing further calculations he realized he could not use two-dimensional polygons to represent all the planets, and instead had to use the five Platonic solids. From this he realized that he had stumbled on a similar ratio to the one between the orbits of Saturn and Jupiter.

According to Kepler's account, he discovered the basis of the model while demonstrating the geometrical relationship between two circles. Thomas Digges had published a defense of Copernicus in an appendix in 1576. This was virtually the first attempt since Copernicus to say that the theory of heliocentrism is physically true. This book explains Kepler's cosmological theory, based on the Copernican system, in which the five Platonic solids dictate the structure of the universe and reflect God's plan through geometry. Kepler proposed that the distance relationships between the six planets known at that time could be understood in terms of the five Platonic solids, enclosed within a sphere that represented the orbit of Saturn. The Cosmographic Mystery, alternately translated as Cosmic Mystery, The Secret of the World, or some variation) is an astronomy book by the German astronomer Johannes Kepler, published at Tübingen in late 1596 and in a second edition in 1621. Kepler's Platonic solid model of the Solar System from Mysterium Cosmographicum
