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
Sun goddess of the Earth Sun goddess of the Earth The Sun goddess of the Earth (Hittite: "taknaš UTU", Luwian: tiyamaššiš Tiwaz) was the Hittite goddess of the underworld. Her Hurrian equivalent was and her Sumerian/Akkadian equivalent was Ereshkigal, both of which had a marked influence on the Hittite goddess from an early date. In the Neo-Hittite period, the Hattian underworld god, Lelwani was also syncretised with her. In Hittite texts she is referred to as the "Queen of the Underworld" and possesses a palace with a vizier and servants. In the Hittite New Kingdom she is attested as the mother of two weather gods.