[mi-ton-ik] 
| a cycle of 235 synodic months, very nearly equal to 19 years, after which the new moon occurs on the same day of the year as at the beginning of the cycle with perhaps a shift of one day, depending on the number of leap years in the cycle. |
| Me·ton·ic cycle (mĭ-tŏn'ĭk) n. A period of 235 lunar months, or about 19 years in the Julian calendar, at the end of which the phases of the moon recur in the same order and on the same days as in the preceding cycle. [After Meton (fl. fifth century B.C.), Athenian astronomer.] |
Metonic cycle
in chronology, a period of 19 years in which there are 235 lunations, or synodic months, after which the Moon's phases recur on the same days of the solar year, or year of the seasons. The cycle was discovered by Meton (fl. 432 BC), an Athenian astronomer. Computation from modern data shows that 235 lunations are 6,939 days, 16.5 hours; and 19 solar years, 6,939 days, 14.5 hours. See also golden number.
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