Join us for Annapolis tutor Khafiz Kerimov's lecture " Ptolemy's Bisection of Mars' Eccentricity."

The Almagest provides very little insight into how Ptolemy arrived at his concepts and models. Ptolemy’s “secrecy” is especially regrettable when it comes to the so-called “equant” (punctum aequans), the powerful (yet potentially heretical) mathematical tool that is arguably Ptolemy’s most important personal contribution to astronomy. Ptolemy’s equant divorces the center around which the planet describes a circular path from the center around which it moves with uniform angular speed. In this lecture I shall argue that, even though Ptolemy first introduces the equant in his account of the inferior planets (specifically Venus) in Bk. IX, he first developed the equant hypothesis in his encounter with the superior planets (Mars, in particular) that only make their appearance later in the Almagest, in Bk. X. So, in this lecture I shall attempt to defend the position that the equant’s origin is Martian rather than Venusian.

This lecture is free and open to the public and will be held in McDowell Hall's Great Hall.