The Metonic cycle is a period of 19 years (235 lunar months), after which the new and full Moons return to the same days of the year. New Moon to new Moon is one cycle. It appears as a thin curved shape, but I think of it as the time when we cannot see the Moon. The Metonic cycle was the basis of the ancient Greek calendar and is still used for calculating movable feasts such as Easter.
Intermission -
To a world full of idiots: Easter is not a pagan holiday. In Latin, it is called Pascha; in Greek, it is called Pascha; and in French, it is called Pâques. Only in Germanic languages does the word “Easter” appear. Easter parallels the German word Ostern, of uncertain origin, but likely deriving from the Catholic designation of Easter week as in albis, a Latin phrase that was understood as the plural of alba (“dawn”) and became eostarum in Old High German. That is how eostarum begot Ostern begot Easter.
Back to math -
“The recurrence is not perfect, and by precise observation the Metonic cycle defined as 235 synodic months is just 2 hours, 4 minutes, and 58 seconds longer than 19 tropical years. Meton of Athens, in the 5th century B.C., judged the cycle to be a whole number of days, 6,940. Using these whole numbers facilitates the construction of a lunisolar calendar … For example, by the 19-year Metonic cycle, the full moon repeats on or near Christmas Day between A.D. 1711 and A.D. 2300.” Wikipedia [slightly edited to clarify time periods]
1711 to 2300 = 589 years
589/19 (the Metonic cycle) = 31
365 days/31 = 11.7741935 (months in a year, not 12)
A question on Quora prompted me to learn what the Metonic (Meton) cycle is.
Intermission -
To a world full of idiots: Easter is not a pagan holiday. In Latin, it is called Pascha; in Greek, it is called Pascha; and in French, it is called Pâques. Only in Germanic languages does the word “Easter” appear. Easter parallels the German word Ostern, of uncertain origin, but likely deriving from the Catholic designation of Easter week as in albis, a Latin phrase that was understood as the plural of alba (“dawn”) and became eostarum in Old High German. That is how eostarum begot Ostern begot Easter.
Back to math -
“The recurrence is not perfect, and by precise observation the Metonic cycle defined as 235 synodic months is just 2 hours, 4 minutes, and 58 seconds longer than 19 tropical years. Meton of Athens, in the 5th century B.C., judged the cycle to be a whole number of days, 6,940. Using these whole numbers facilitates the construction of a lunisolar calendar … For example, by the 19-year Metonic cycle, the full moon repeats on or near Christmas Day between A.D. 1711 and A.D. 2300.” Wikipedia [slightly edited to clarify time periods]
1711 to 2300 = 589 years
589/19 (the Metonic cycle) = 31
365 days/31 = 11.7741935 (months in a year, not 12)
A question on Quora prompted me to learn what the Metonic (Meton) cycle is.
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