Synodic Month (mo (syn))

AstronomicalCurrent unitApproximate value

About 29.53 days, the time from one new moon to the next. The basis of lunar and many religious calendars.

1 synodic month = 2,551,442.976 seconds (approximately).

Approximate value. Standards for the synodic month varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

About the synodic month

A synodic month is the span from one new moon to the next, when the Moon returns to the same position relative to the Sun as seen from Earth. Its mean length is about 29.53 days, or 29 days 12 hours 44 minutes 3 seconds. The word synodic derives from a Greek term for meeting, since the Sun and Moon meet in the sky at each new moon.

Individual months are far from equal. Because the Moon's orbit is elliptical and the Sun perturbs it, a single lunation can run from about 29.27 to about 29.83 days, and in a given year the interval can differ from the mean by up to roughly seven hours. In 2001, for instance, lunations ranged from 29 days 19 hours in January to 29 days 7 hours in July.

Babylonian astronomers were the first to recognise this kind of month and to work out its mean length, and the quantity still underlies lunar and lunisolar calendars such as the Islamic, Hebrew and Chinese ones. It is longer than the sidereal month of about 27.3 days because Earth moves along its orbit while the Moon circles it.

Sources: Wikipedia: Lunar month

Synodic Month conversion chart

1 synodic month expressed in every other time unit:

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