Metonic cycle

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Metonic cycle:

see synodic periodsynodic period
, in astronomy, length of time during which a body in the solar system makes one orbit of the sun relative to the earth, i.e., returns to the same elongation.
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Metonic cycle

(me-ton -ik) (lunar cycle) A period of 19 years (tropical) after which the phases of the Moon recur on the same days of the year: the period contains 6939.60 days, which is very nearly equal to 235 synodic months, i.e. 6939.69 days. Since it is also almost equal to 20 eclipse years, i.e. 6932.4 days, it is possible for a series of four or five eclipses to occur on the same dates at intervals of 19 years. The cycle was discovered by the Greek astronomer Meton in the fifth century bc and was used in determining how intercalary months could be inserted into a lunar calendar so that the calendar year and the tropical (seasonal) year were kept in step.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Metonic Cycle

(religion, spiritualism, and occult)

The ancient Greek Meton discovered that the Moon has a cycle of 19 years, after which a new moon occurs on the same day of the year.

The Astrology Book, Second Edition © 2003 Visible Ink Press®. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Metonic Cycle


a time interval of 6,940 days used for bringing into agreement the length of a lunar month and solar year in a lunisolar calendar. It was proposed in 433 B.C. by the Athenian scholar Meton and was the foundation of the ancient Greek calendar. The Metonic cycle is related to the approximate (to within several hours) equation 19 tropical years = 235 synodic months. The Metonic cycle contains 19 years—12 years of 12 months each and seven years of 13 months each. Out of these 235 months, 125 months are called full months, that is, they have 30 days each, and the remaining 110 months are called hollow months and have 29 days each. The Metonic cycle is also used in the Jewish and ancient Christian calendars.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

metonic cycle

[me′tän·ik ′sī·kəl]
A time period of 235 lunar months, or 19 years; after this period the phases of the moon occur on the same days of the same months.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
This period of time is now known as the Metonic cycle and served as the basis for the Babylonian calendar from which the Jewish calendar was originally derived.
With the Metonic cycle as background the basic structure of the Jewish calendar can be easily described qualitatively.
The present study does not seek to address the extended lifespan of several figures in the antediluvian generations, for which there are already at least two competing explanations, one based on the "Metonic Cycle" and one based on the "sexagesimal system augmented by seven." (1) Likewise, this study does not consider why or when this particular system ended and another began.
(1.) Considering the ages of a number of the antediluvian lives, see the "Metonic Cycle" which is based on 19 years.
The 2005 annular eclipse in Madrid, Spain, was one Metonic cycle from the 1986 eclipse.
Eventually the Greeks adopted a more accurate period known as the Metonic cycle, which equates 19 solar years with 235 lunar months.
You may already have guessed that the 19 steps correspond to the 19 years in the Metonic cycle, a Babylonian find rediscovered by Meton in Athens in the 5th century B.C.
It turns out that there is another cycle inside the Metonic cycle with a slightly faster beat.