Orrery on display in Kassel at the Astronomisch-Physikalisches Kabinett and in Dresden at the Mathematisch-Physikalischer Salon. In "De revolutionibus orbium coelestium", published in Nuremberg in 1543, Nicolaus Copernicus challenged the Western teaching of a geocentric universe in which the Sun revolved daily around the Earth. He observed that some Greek philosophers had proposed a heliocentric universe. This simplified the apparent epicyclic motions of the planets, making it feasible to represent the planets' paths as simple circles. This could be modelled by the use of gears. Tycho Brahe's improved instruments made precise observations of the skies (1576–1601), and from these Johannes Kepler
Theory of the Earth evidence of the past action of processes which still operate today. He also anticipated natural selection, as follows: Hutton's prose hindered his theories. John Playfair in 1802 restated of Huttton's geological ideas in clearer English. However, he left out Hutton's thoughts on evolution. Charles Lyell in the 1830s popularised the idea of an infinitely repeating cycle (of the erosion of rocks and the building up of sediment). Lyell believed in gradual change, and thought even Hutton gave too much credit to catastrophic changes. Hutton's work was published in different forms and stages: Theory of the Earth Theory of the Earth