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
Christianity in the 16th century thereby turning the Grand Duchy of Moscow into Tsardom of Russia, as it was called in the coronation document. The growing might of the Russian state contributed also to the growing authority of the autocephalous Russian Church. Realizing the necessity of strengthening the ecclesiastic authority in Russia, Boris Godunov managed to persuade the Ecumenical Patriarch of Constantinople Jeremias II to establish a patriarchate in Russia. In 1589, Metropolitan Job of Moscow became the first Patriarch of Moscow and all the Rus', making the Russian Church one of the Orthodox patriarchates. Christianity in the 16th century In 16th-century Christianity, Protestantism came