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
Paris in the 16th century the 16th century, Paris became first in Europe in book publishing. In 1530, Françis I created a new faculty at the University of Paris with the mission of teaching Hebrew, Greek and mathematics. It became the "Collège de France". In 1540, the Jesuit order established its first schools in Paris. In 1549, the first textbook of the French language, "Defense et illustration de la langue Française", by Joachim de Ballay, was published. Francis I died in 1547. His son, Henry II, made his official entrance into Paris in 1549 with a lavish procession and ceremony; the first Renaissance fountain in