Holidays in other calendars this month

There will be a lunar conjunction on 8 September 2010 (MJD 55447.4375), which means that the moon will pass between the earth and the sun, which happens about once a month.  This is also known as an astronomical new moon, although traditionally a new moon is usually observed about a day later, when the crescent moon first becomes visible in the evening sky.  In lunar calendars, this crescent moon marks the beginning of a new month.

One such calendar is the Hebrew or Jewish calendar.  Sunset on 8 September will mark the beginning of the month of Tishrei and Jewish year 5771, and the holy day of Rosh Hashanah.  Although the Jewish calendar has months based upon the phases of the moon, it keeps track of the seasons by sometimes adding a thirteenth month to the year, since the solar year is about eleven or twelve days longer than twelve months.

Another lunar calendar is the Muslim calendar.  The crescent new moon marks the end of the holy month of Ramadan, and the feast of Eid ul-Fitr.  The Muslim calendar is not predetermined, but based rather upon actual observations of the moon, so that while it is expected to occur around 10 September, it may be a day or two before or after, and varies from place to place, depending upon local observers.  Unlike the Jewish calendar, the Muslim calendar does not keep track of the seasons and always has exactly twelve months in a year, so Ramadan comes about eleven days earlier every Gregorian year.

In the solar Gregorian calendar, September is the month containing the equinox marking the beginning of autumn in the northern hemisphere.  This year, the equinox occurs on 23 September in the eastern hemisphere, and 22 September in the western. (MJD 55462.13111)

The French Republican calendar, used during the French Revolution, begins each year on the day this equinox occurs in Paris, which is in the eastern hemisphere, so by this rule Republican year CCXIX begins on 23 September, which means that a leap day must be added to the end of the current year CCXVIII.

However, the calendar has not been in official use since 1805, and some people use different leap year methods to determine the beginning of the calendar year.  Brumaire uses a rule similar to the Gregorian calendar, but since historically the years III, VII and XI were leap years, the leap day is usually inserted at the end of the year previous to one divisible by four.  That means that there is none this year (218), and in the Salute et Fraternité app the year CCXIX begins on 22 September 2010 instead of 23 September.

The Calendrier app offers a choice of two different rules, either the original equinoctial rule which starts the year on 23 September, or the Gregorian-style rule proposed by Gilbert Romme during the Revolution, which starts the year on 22 September.

MJD 55443.893
Octidi 18 Fructidor an CCXVIII à 9hd t.m.P.

1 comment:

  1. I can't wait for the new French Republican year. I'm going by TMP (temps moyen de Paris/Paris Mean Time), UTC and EDT (Eastern Daylight Time). I will do a mini celebration here at ELITE 3000 on the 22nd. I will create a Flash clock that shows the French Republican Calendar date and French Revolvuntery time in both analog and digital.