De revolutionibus orbium coelestium divided into six "books" (sections or parts), following closely the layout of Ptolemy's "Almagest" which it updated and replaced: Copernicus argued that the universe comprised eight spheres. The outermost consisted of motionless, fixed stars, with the Sun motionless at the center. The known planets revolved about the Sun, each in its own sphere, in the order: Mercury, Venus, Earth, Mars, Jupiter, Saturn. The Moon, however, revolved in its sphere around the Earth. What appeared to be the daily revolution of the Sun and fixed stars around the Earth was actually the Earth's daily rotation on its own axis. Copernicus adhered
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