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
Allegory of the Planets and Continents orbiting the Sun. The cornice of the painting symbolize the continents Europe, America, Africa, and Asia. Allegory of the Planets and Continents Allegory of the Planets and Continents is an 18th-century painting by Italian artist Giovanni Battista Tiepolo. Done in oil on canvas, the allegorical work uses human figures to represent members of the Greco-Roman pantheon, the planets, and four continents. The painting is an elaborate oil sketch made by Tiepolo in preparation for rendering a similar, larger version of his scene. Tiepolo's work was painted to be hung above a staircase of the Wurzburg Residence in Wurzburg, Germany. The