VARIOUS CYCLES

The Moon and Earth follow several important cycles that shape calendars and timekeeping.

- By Lalit Dube

The Sidereal Month is the time the Moon takes to complete one orbit around the Earth, lasting 27.32 days. However, the period between two successive Full Moons, called the Synodic Month, is longer at 29.53 days. A Full Moon occurs when the Sun, Earth, and Moon are aligned. After a Sidereal Month, the Moon does not align perfectly with the Sun and Earth because Earth has moved in its orbit. Hence, the Moon must travel slightly more to form the next line, making the Synodic Month longer. Indian calendars (Panchang) follow the Synodic Month as a month.