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Sola-Luna cycles.

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#1 JohnLF

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Posted 21 November 2020 - 10:40 PM

Hi, an online book from 1894 AD, claimed 2300 years and 1260 years is a Sola-Luna cycle.

 

I am wondering how to describe that in an Astronomy in the Bible outreach I am planning for February in North New South Wales, Australia.

 

What would be the definition of a Luna-Solar Cycle. 



#2 zleonis

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Posted 22 November 2020 - 11:33 PM

I think this is referring to lunisolar (as I've usually seen it written) cycles where there are very nearly whole numbers of lunar months in a period of years. The best known of these is the Metonic cycle of 19 years, in which there are 235 lunar months (cycles of the moon's phases). For example, there will be a full moon on November 30, 2020, and also nineteen years from now on November 30, 2039.

 

There are lots of other periods of years where the lunar phases would repeat on about the same day, with allowances for leap years, etc. It looks like periods of 2300 years and 1260 years would come reasonably close to comprising an integer number of lunations - although not as close as the 19 year Metonic cycle (there are 60 periods of years shorter than 2300 years that are in closer sync than the 2300 year period). 

 

Some internet searching showed that the numbers 2300 and 1260 are found in the Bible - 2300 in Daniel, in reference to the number of days that  a sanctuary would be desecrated, and 1260 in Revelation, (the number of days for which some sackcloth-clothed witnesses prophesied, and also how long the dragon's mother was nourished after she fled to the place prepared by God for her in the wilderness). In the 18th Century, a French astronomer (and apparently, minute reader of the Bible) Jean-Philippe Loys de Cheseaux noticed that these two numbers were close-ish to a lunisolar cycle, and that (crucially?) their difference (1040) is also a close lunisolar cycle (about 15 minutes better than the Metonic cycle, but not so close as some shorter cycles).



#3 JohnLF

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Posted 23 November 2020 - 08:01 PM

I think this is referring to lunisolar (as I've usually seen it written) cycles where there are very nearly whole numbers of lunar months in a period of years. The best known of these is the Metonic cycle of 19 years, in which there are 235 lunar months (cycles of the moon's phases). For example, there will be a full moon on November 30, 2020, and also nineteen years from now on November 30, 2039.

 

<…snip…>

I found this reference in chapter 11 of a book by H. Grattan Guiness -- hope that I spelt his name correctly.   And yes these numbers are found in the Bible.  He said that there is a 315 year cycle, and that the 1260 years are 4 times that 315 year cycle.  Am aware the Jews used a 19 year Cycle.  

 

Sir Isaac Newton [died 1727AD], the famous scientist & Astronomer, was also a Hebrew Scholar.  In his commentary on Daniel he said this 2300 days of Daniel 8:14 are 2300 years.  And many medieval Rabbis also said the 2300 days are years as did many protestant commentators before and after Isaac Newton. 

 

But was after a definition of the "Soli-Lunar cycle I was after.  

 

From one website we read:--

 

"hus Guinness’ main chronological discoveries are;

- That 2,300 years is not simply a soli-lunar cycle but a soli-lunar-anomalistic cycle...."

 

Seems I need to do some more online research on this.  Am only on internet two days a week.



#4 zleonis

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Posted 23 November 2020 - 10:07 PM

I couldn't speak to the religious significance of the cycles, but the soli-lunar cycle would be a cycle of years in which the calendar date and the phase of the moon come back into sync. A soli-lunar-anomalistic cycle would be a cycle in which the calendar day, lunar phase, and the moon's distance from Earth all repeat.

 

As you may know, an anomalistic month is the time it takes for the moon to return to its closest approach to Earth. It's a couple days shorter than the synodic month (cycle of lunar phases) because the moon orbits the Earth in the same direction as they orbit the sun, so the moon has some ''catching up' to do to return to a given phase.

 

The calendar dates of lunar perigee do not quite follow a 2300 cycle, it's off by about a day and a half.




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