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 Paris in the 16th century During the 16th century, Paris was the largest city in Europe, with a population of about 350,000 in 1550. The 16th century saw the Renaissance arrive in Paris, expressed in the city's architecture, art and cultural life. The Kings of France returned to Paris from the Loire Valley. Paris. In 1534 Francis I became the first French king to make the Louvre his residence. Under King Francis I, the Renaissance style of architecture, imported from Italy, was widely used in churches and public buildings, replacing the gothic style. Paris landmarks built during the 16th century