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
Earth, Moon, and Planets Earth, Moon, and Planets Earth, Moon, and Planets is a peer-reviewed scientific journal, published approximately ten times per year by Springer Science+Business Media. It was established in 1969 under the title "The Moon", was known as "The Moon and the Planets" from 1978 to 1983, and was first published under the current title in February 1984. The editor-in-chief is Murthy S. Gudipati (Caltech and JPL). The journal's main focus is on research about the Solar System. Besides original research articles, "Earth, Moon, and Planets" publishes conference proceedings, review articles, book reviews, and special issues. "Earth, Moon, and Planets" focuses on