time between two successive passages of the Moon through the ascending node of its orbit and the ecliptic was different from the anomalistic month and synodic month. This period is now called the <i>draconic month</i> or <i>nodal month</i>. The non-uniform motion of the Moon and its passage through the nodes are important in the eclipse prediction. As a result, two additional conditions were added to the superior epoch: it had to be the instant when the Moon was at perigee (or apogee) and at the ascending (