Talk:Metonic cycle

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Moon Phases[edit]

To me this article is missing something quite important, that is the affect of the cycle on moon phases: that the moon returns to the same celestial longitude and same lunar phase on the same calendar date every 19 years. (talk) —Preceding undated comment added 02:56, 13 June 2016 (UTC)

Other Greek references[edit]

What is this Greek thing all about? Wikipedia's other articles state that Odysseus returned after 20 years, which is longer, not "at the exact moment when one Metonic cycle has passed." I think some clarification is in order. (talk) 03:40, 21 February 2008 (UTC)

I'm going to be bold and remove that bit. Markfiend (talk) 15:47, 14 April 2009 (UTC)

This reference to the Antikythera Mechanism seems to be hanging with no real reference. Dr.sliderule (talk) 04:08, 8 March 2015 (UTC)

Further Details[edit]

I'm removing the reference to the Quran, it seems to me to be a) irrelevant and b) spam. Markfiend (talk) 12:54, 9 April 2009 (UTC)

How is the reference to the Qur'an "irrelevant"? And how do you define 'spam'? They certainly weren't selling anything. - Brad Watson, Miami (talk) 15:07, 21 May 2012 (UTC)
That the Quran mentions the word 'year' 19 times doesn't help us understand anything that I can see, and the link to other Quranic numerology is even less relevant. I wouldn't call it "spam", exactly, but spam need not be commercial; the defining element is cluttering up communications channels to gain attention. —Tamfang (talk) 17:49, 21 May 2012 (UTC)

Reverted claim[edit]

This claim was added by:, replacing previous text.

This cycle can actually be explained with general relativity. Full details cannot be described here, and the reader is refered to the paper by Miles Mathis on the Metonic Cycle in the General Science Journal.

I found the paper: [1], and variation[2] at the author's website. There's no publishing date, no references in the paper. On a quick look I have no clear reason to believe it is more than the author's unproved speculation. Tom Ruen (talk) 19:07, 3 July 2009 (UTC)

word order in first sentence[edit]

I'm aware that WP guidelines are to place the words in bold as early in the sentence as possible. However, the guideline does not say the bold words must be first. Nor does it say 'you must contort the normal word order of English syntax in order to place the bold words first' nor 'the bold words must come first even if it makes the sentence harder to understand or read.' I'm also aware that there are editors who prowl articles in order to make just these kinds of changes. There are probably better uses of time.

In my view, this article is an example of how readers can be served by a phrase orienting them to the context of the topic before dropping the bold words. Cynwolfe (talk) 16:48, 5 July 2010 (UTC)

19 years or 254 lunar orbits?[edit]

(Because this article is called a "cycle" the edit correlates the interval with actual cycles, lunar orbit, rather than the period of 19 years. Follow the external link for more on this.)

What, a year isn't a cycle?? —Tamfang (talk) 18:57, 14 December 2010 (UTC)

I disagree. It correlates with BOTH 19 tropical years AND 235 synodic months and so 254 lunar orbits. That is what makes it notable. The lunar orbit is less significant than the synodic month. Karl (talk) 11:26, 15 December 2010 (UTC)

I restored the 254 lunar orbit correlation (that was removed from the intro). I agree 235 lunations is more important, since that's what we see, and what defines lunar calendars. I admit I don't quite see the meaning of the 254 match, ought to be explained. Why is 19 years so close to 254 lunar orbits? Tom Ruen (talk) 23:01, 15 December 2010 (UTC)
235 = 254−19.
I would make 235 lunations the primary definition of the cycle, because of how it is used: 235 exact lunations are (or anciently were) used to approximate 19 tropical years. Of course it's quantized by days but that noise cancels out on average. —Tamfang (talk) 00:19, 16 December 2010 (UTC)
Good answer! :) Tom Ruen (talk) 02:38, 16 December 2010 (UTC)

p.s. I also added "255 draconic months (lunar perigees nodes) = 6939.1161 days" since this match is what makes it an eclipse cycle, repeating for 4-5 eclipse events. Tom Ruen (talk) 23:19, 15 December 2010 (UTC)

I see that you spotted your booboo. —Tamfang (talk) 05:29, 16 December 2010 (UTC)

'There Are No Coincidences - there is synchronism'[edit]

There is a definite connection between the 29.5 day lunar/synodic month, 355 day lunar year, 365.25 solar/tropical year, the Julian/Gregorian Calendar, and "7_4". The ancient Egyptians (and eventually others) practiced sacred geometry with its primary premise of "As above, so below". They observed (with the naked eye) that there are 7 moving objects in the heavens ("7 heavens") and 4 of these do NOT cast shadows on Earth (Venus does). They observed the lunar monthly cycle of 29 1/2 days as 4 phases of roughly 7 days each (~7.4 days). The Moon thus gives us the 7-day-week and the 4-week 'moonth'. The ancients observed that the 12-month lunar year (354 day) + a 7-day-week + 4 days = solar/tropical year. (7.4 x 4 = 29.6 x 12 = 355.2 + 7 + 4 = 366.2 leap year).

The Roman and Egyptian astrology (astronomy) advisors to Roman Emperor Julius Caesar brought this "Combination of 7 & 4 from the gods" to his attention. He then decreed that the Roman Calendar be adjusted to 365 days by having 7 31-day-months + 4 30-day months + February's 7-day weeks x 4 weeks + the 'leap day' every 4 years.

Sometime after Kepler & Galileo, the mean distance from the Sun of the inner planets were calculated at Venus .7 AU & Mercury .4. Besides Earth, in this solar system there are 7 planets and 4 Trans-Neptunian Plutoids.

---INCOMPLETE--- - Brad Watson, Miami (talk) 22:37, 21 May 2012 (UTC)

Strong Law of Small NumbersTamfang (talk) 22:49, 21 May 2012 (UTC)

How long the Metonic cycle?[edit]

It's not immediately clear from the article if there is any precise definition of the cycle. So it's not clear how long the cycle is. Candidates provided include:

  • a period of very close to 19 years
  • this 6,940-day cycle
  • the unrounded cycle [of slightly less than 6,940 days]
  • 19 tropical years
  • 235 synodic months (lunar phases) = 6,939.688 days (Metonic period by definition).
  • the 19-year-long Metonic cycle [upon which the Runic calendar is alleged to be based]

Perhaps there are several cycles, of nearly the same length, each called the Metonic cycle. Whatever the case, compare the Wikipedia article to entries found at

  • 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. [based on Random House Dictionary]
  • a cycle of nearly 235 synodic months after which the phases of the moon recur on the same days of the year [Collins English Dictionary]
  • 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...Computation from modern data shows that 235 lunations are... [Encyclopedia Britannica]

I'll give this article a few weeks for someone with better knowledge of the subject to fix it. If it's not clarified during that time, then I'll change the first paragraph so that the cycle is 235 synodic months by definition, as claimed already in the 2nd section, and add relevant citations to the reference section. (talk) 19:13, 30 December 2014 (UTC)

Pretty much what it says... very close to 19 full years (or equally, 235 full synodic months), where the number of days of full cycles of the moon very closely matches the number of days in full years. Whether you measure by years, synodic months, or days, it doesn't matter since they measure approximately the same length of time.
So, I'm not sure what part you want clarified in the article.
If you mean which measure is the exact cycle length defined by, there can't be since the length of time is an approximation of two independent cycles (that of the moon around the earth in relation to the sun, and that of the Earth around the sun in relation to a position on the ecliptic). If you wanted to an as close to prefect measure for something (such as for calculations in a program), you would calculate using both the synodic month length and the tropical year length and find at what point the two most closely approach each other. If you tried using a fixed length for the metonic without using the synodic month or the tropical year, after a certain number of cycles, your calculation will be completely off, thus the reason you have to consider the synodic month and the tropical year (along with their variation and change over periods of time) and not the metonic for any precise long term calculations. In short, the Metonic cycle is just a handy approximation and does not (and can not) have an exact precise defined length. — al-Shimoni (talk) 13:21, 25 January 2015 (UTC)