Convert Synodic Months to Seconds

Convert Synodic Months (syn.mo) to Seconds (s) instantly and accurately.

Conversion Formula

s = syn.mo × 2551442.877

About Synodic Months

A synodic (lunar) month = new moon to new moon = 29.5306 days = 2,551,442.9 s. Longer than the sidereal month (27.32 d) because Earth advances ~27° in its orbit during that time; the Moon must travel further to realign with the Sun. Islamic Hijri, Hebrew lunisolar, and Chinese calendars are built on synodic months. Eclipses repeat via the Saros cycle (18 yr 11 d = 223 synodic months). 1 syn.mo ≈ 29.5306 d.

About Seconds

The second (s) is the SI base unit of time, defined since 1967 as exactly 9,192,631,770 periods of the caesium-133 ground-state hyperfine transition at 0 K. Caesium fountain clocks realise this to ~10⁻¹⁶ (1 s lost per ~300 million years); optical lattice clocks (Sr, Yb) reach ~10⁻¹⁸. The second links to the metre via the defined speed of light c = 299,792,458 m/s exactly. 1 s = 1,000 ms = 1/60 min.

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