Lunation

loo-NAY-shuhn

Definition

A lunation is one full cycle of the Moon's phases — the run from one Sun-Moon conjunction (the New Moon), through First Quarter, the Full Moon (when Sun and Moon stand opposite), and Last Quarter, back to the next conjunction. This cycle, the synodic month, averages about 29.531 days; Hunger and Pingree report the Babylonian System B value as 29;31,50,8,20 days — the same figure Hipparchus knew. The chart cast for the New Moon (or Full Moon) just before a date you care about is read as the working lunation chart for the stretch until the next.

In Tradition

Across traditions, the lunation cycle organises month-scale timing: a New Moon opens a month-long theme, a Full Moon marks culmination and awareness. The pre-natal lunation — the most recent New or Full Moon before your birth — is treated in Hellenistic and Arabic-medieval practice as a long-running significator of the themes you carried in. In modern Western practice, Dane Rudhyar's person-centered school, in The Lunation Cycle, builds the waxing New-to-Full and waning Full-to-New halves into a framework of developmental phases.

In Practice

For natal work, an astrologer finds the pre-natal lunation by working out the most recent New or Full Moon before your birth and noting its sign, degree, and house in your chart; this is the alignment that underlies the Hellenistic techniques for length of life and length of the mother's pregnancy, and it is also read as a long-arc significator. For mundane and electional timing, the chart is cast for each New and Full Moon at the relevant place; the lunation's sign, house, and aspects to natal points are read as the themes stirred for the two-week half-cycle that follows. Lunations falling within a tight orb of birth planets, angles, or lots are watched especially closely.

Historical Origin

The synodic month is the basic time-unit of every ancient lunar calendar and the core period-relation of both Babylonian System A and System B. Hunger and Pingree document the System B value of 29;31,50,8,20 days and its scheme of whole-month prediction intervals. The pre-natal lunation as a natal significator is attested in Hellenistic sources (Ptolemy, Valens) and developed in Arabic-medieval practice. The 20th-century person-centered framework of phases was developed by Dane Rudhyar in The Lunation Cycle.

Definition

In Tradition

In Practice

Historical Origin

Further Reading