[Pramāṇa](https://indike.org/pramana/) › [Studies](https://indike.org/pramana/ins) › [Science, technology and education](https://indike.org/pramana/ins.science) › [Jyotihshastra: Astral and Mathematical Literature](https://indike.org/pramana/ins.science.pingree-1981) › c4.34 # Jyotihshastra: Astral and Mathematical Literature c4.34 Jyotiḥśāstra: Astral and Mathematical Literature c4.34 - **Language:** English ### [c4.34](https://indike.org/pramana/ins.science.pingree-1981.c4.34) By the early fifth century when the Brāhmapakṣa began there had been introduced into India a more sophisticated form of Greek astronomy characterized by planetary models comprising the combination of an eccentric deferent with an epicycle (but without Ptolemy’s equant or special model for Mercury), or a Peripatetic model with two independent epicycles whose centers are carried by a concentric deferent,¹⁵ or one in which each inequality is accounted for by a concentric circle with an equant.¹⁶ The inequalities in the motions of the Sun and the Moon are computed by means of an eccentric, a concentric deferent with an epicycle (the preferred model), or a concentric circle with an equant; in the earlier part of the Greek period Ptolemy’s second lunar inequality was not known, though it was introduced into India from Islamic sources in the tenth century. - [Previous: c4.33](https://indike.org/pramana/ins.science.pingree-1981.c4.33) - [Next: c4.35](https://indike.org/pramana/ins.science.pingree-1981.c4.35) - [Up: c4](https://indike.org/pramana/ins.science.pingree-1981.c4) --- Source: [https://indike.org/pramana/ins.science.pingree-1981.c4.34](https://indike.org/pramana/ins.science.pingree-1981.c4.34) · Pramāṇa