Metonic cycle

The Metonic cycle or Enneadecaeteris in astronomy and calendar studies is a particular approximate common multiple of the year (specifically, the seasonal i.e. tropical year) and the synodic month. Nineteen tropical years differ from 235 synodic months by about 2 hours. The Metonic cycle's error is one full day every 219 years, or 12.4 parts per million.
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Period of 235 lunations or about 19 years. devised by Meton, an Athenian astronomer (5th century B.C.) for the purpose of obtaining a period 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.

Eng: metonic cycle
Urdu: مِٹونی چَکّر ۔ مِٹونی دور ۔ دورِ قَمر ۔