The Synodic Month
The average time from one New Moon to the next — about 29.53 days. It is the cycle of the Moon’s phases as seen from Earth, and the ‘month’ at the root of lunar and lunisolar calendars.
Phases, not orbit
The synodic month is longer than the time the Moon takes to circle the Earth against the stars (the sidereal month, about 27.3 days). While the Moon orbits, the Earth moves on around the Sun, so the Moon needs a little extra time to catch up to the same phase — the difference between 27.3 and 29.5 days.
Why it drifts from the calendar
Because 29.53 days does not fit neatly into a solar year, the Moon’s phases fall on different calendar dates each month — the very drift the Metonic cycle was devised to tame.
Its role
The synodic month sets the rhythm of New and Full Moons — the pulse Moonlit reads for you, aligned to your own chart and where you stand.
Connections
- The Metonic Cycle — A period of about nineteen years after which the phases of the Moon fall on very nearly the same days of the solar year. 235 lunar months are almost exactly nineteen solar years — a near-perfect reconciliation of the Moon’s months with the Sun’s year.
- The Lunar Nodes — The two points where the Moon’s orbit crosses the ecliptic — the Sun’s apparent path. The ascending (North) node and descending (South) node drift slowly backward through the zodiac, and eclipses can happen only when a New or Full Moon falls near one of them.
- The Void of Course Moon — The stretch of time when the Moon, having made its last major aspect in a sign, will make no more before it moves into the next. It is traditionally read as a pause — a time to rest and reflect rather than to begin something new.