What is a 'black moon'? Why May's new moon has an unusual name.

May 19, 2023
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The math is not right on any of the calculations that claim 29,5d

You can count the phase lenghts yourselves, those are always with extra 24hrs.

Here is example of the range May 19 to June 18:

May 19th
18:53

Day of new moon has 5hrs 7minutes inside May new moon range.

The rest of the days on may are 11 full 24hrs days (May has 31 days) inside this new moon range (or lunar phase)

June 18th
07:37

June has 17 full 24 hrs days inside this range still plus 7hrs 37minutes (the next New Moon predictation in June)

Those equals to 28 days and 13hrs 42 minutes. That is ruffly 28,5 days and NOT 29,5 as been told.

 
May 19, 2023
2
0
10
The math is not right on any of the calculations that claim 29,5d

You can count the phase lenghts yourselves, those are always with extra 24hrs.

Here is example of the range May 19 to June 18:

May 19th
18:53

Day of new moon has 5hrs 7minutes inside May new moon range.

The rest of the days on may are 11 full 24hrs days (May has 31 days) inside this new moon range (or lunar phase)

June 18th
07:37

June has 17 full 24 hrs days inside this range still plus 7hrs 37minutes (the next New Moon predictation in June)

Those equals to 28 days and 13hrs 42 minutes. That is ruffly 28,5 days and NOT 29,5 as been told.

Same applies to Spring Equinox (solar year) calculations as well, the March 20th (or in Leap years it falls on 19th), 79th day in Gregorian Year Cycle anyhow, and it is counted twice, giving the calculation additional 24hrs extra.

If one calculated strictly full days and the rest with ranges, the sum is always 364 days 5hrs and ~58 minutes.

There is never more than 363 days full inside the range, and the rest 29-30hrs that comes from both splits of 79th Spring Equinox days always make only 1 full day and ~5-6hrs.