Comments on All you ever wanted to know about the calendar

jonas (2020-10-22T19:35:12Z)

Let me collect some relevant links here. Besides your calendar and time pages, you have a blog entry explaining why it's hard to even model the Earth's movement <URL: http://www.madore.org/~david/weblog/d.2012-04-15.2030.rotation-terre.html >. Aside from your pages, Claus T√łndering's calendar FAQ <URL: https://www.tondering.dk/claus/calendar.html >, John Savard's writeups about calendars <URL: http://www.quadibloc.com/science/calint.htm >, and timeanddate.com's articles <URL: https://www.timeanddate.com/topics/ > are also useful. They explain, in particular, the Jewish calendar, which is a combined lunar-solar calendar used to compute the date of Jewish holidays, and that your pages don't explain at all. I'm also told that <URL: https://individual.utoronto.ca/kalendis/ > and <URL: http://myweb.ecu.edu/mccartyr/calendar-reform.html > have some information about calendars.

Ruxor (2003-11-07T16:44:35Z)

I don't think any lunar calendar is "actually used". Who would use such a thing?

But if I were to select one, without hesitation I would choose the one where all lunar months are 29 or 30 days, because that is a principle behind the Meton-Callippus cycle. The epact tables should be considered only an approximation to that "real" calendar, one which gives the right date for Easter. Naturally, I have no authority and speak only for myself.

Karl (2003-11-07T14:58:16Z)

This is a very interesting web page. It has already provoked a lot of discussion. I agree that calendars do deal with days rather than time.

This web page shows two different approaches to making the Gregorian lunisolar calendar. Both give the same date for the Easter full moon, but may differ at certain other dates.
One has all lunar months with 29 or 30 days, the other has lunar months starting on the same Gregorian date in the year regardless of the leap days.

Does David know which one is actually used?


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