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 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