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 Protestants were killed in the streets by Catholic mobs. At the end of the century, Henry IV was able to return to Paris as King, and permitted Protestants to open churches outside the city. Urban innovation in Paris during the 16th century included the first street lighting, by candles.The first theater opened in Paris in 1548, and the first ballet performance took place at the French court in 1581. At the beginning of the 16th century Paris was officially the capital of France, but the King, Louis XI, had little trust in the Parisians, and resided in the chateaux of