De revolutionibus orbium coelestium have begun work on his new system by that time. Most historians believe that he wrote the "Commentariolus" after his return from Italy, possibly only after 1510. At this time, Copernicus anticipated that he could reconcile the motion of the Earth with the perceived motions of the planets easily, with fewer motions than were necessary in the "Alfonsine Tables", the version of the Ptolemaic system current at the time. In particular, the heliocentric Copernican model made use of the Urdi Lemma developed in the 13th century by Mu'ayyad al-Din al-'Urdi, the first of the Maragha astronomers to develop a non-Ptolemaic
A New Theory of the Earth A New Theory of the Earth A New Theory of the Earth was a book written by William Whiston, in which he presented a description of the divine creation of the Earth and a posited global flood. He also postulated that the earth originated from the atmosphere of a comet and that all major changes in earth's history could be attributed to the action of comets. It was published in 1696 and was well received by intellectuals of the day such as Isaac Newton and John Locke. The book is organized as follows: In the introduction, Whiston discusses the Mosaic