Timeline of astronomy Rectification of Planetary Theory", eliminated the need for an equant by introducing an extra epicycle, departing from the Ptolemaic system in a way very similar to what Copernicus later also did. Ibn al-Shatir proposed a system that was only approximately geocentric, rather than exactly so, having demonstrated trigonometrically that the Earth was not the exact center of the universe. His rectification is later used in the Copernican model. Nicolaus Copernicus publishes "De revolutionibus orbium coelestium" containing his theory that Earth travels around the Sun. However, he complicates his theory by retaining Plato's perfect circular orbits of the planets. A brilliant
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