A Glimpse of Non-Ptolemaic Astronomy in Early Hay’a Work – Planetary models in ps. Mashā’allāh’s Liber de orbe

Recently I identified two Arabic manuscripts containing the Arabic original of a Latin work entitled Liber de orbe attributed to Māshā'allāh, and identified the title and author of the Arabic Liber de orbe as Book on the Configuration of the Orb written by Dūnash ibn Tamīm. This identification confirms that it is one of the earliest works on `ilm al-hay’a in Western Islam. In this article, I attempt to illustrate the details of its astronomical contents, and to determine its significance as an early hay’a work in Western Islam. The analysis reveals that although it explicitly refers to the name of Ptolemy, this work transmits non-Ptolemaic planetary system based on an eccentric-epicycle model. And by using a piece of the non-Ptolemaic materials that this work accidentally preserves in the name of Ptolemy as a criterion of determining what was the original achievement by Ptolemy, I show that one of his innovations was building a lunar model by using an epicycle model of the Sun and introducing an eccentric to it.