Our Book Club meeting this month was delayed to avoid Rosh Hashanah, prompting me to investigate that holiday. My initial investigation determined that it was Jewish New Year, celebrated on the first day of the seventh month of the Jewish calendar. I also learned that this calendar was a lunar one and that its first month, Nisan, occurs coincident with the first new moon after the vernal equinox. In addition, Rosh Hashanah is the anniversary of the Creation of the Earth, halfway through year one, 5781 years ago.
Armed with this new knowledge I set out to make fun of my Jewish friends; after all, who ever heard of New Year’s Day falling in the middle of the year? However, remembering the old adage, “Don’t throw stones if you live in a glass house!”, I changed my mind. What is more absurd that our calendar, with the ninth month being named September, and with months varying in length from twenty-eight days to thirty-one? Perhaps I would be better off researching the origin of our calendar.
Our current calendar is descended from an ancient Roman calendar which ran from the vernal equinox to the winter solstice, the portion of the year devoted to agriculture. It consisted of thirty-eight weeks, each eight days long. This eventually was replaced by ten months, with seven day weeks.
The first month was named for the Roman god of war, Mars, the ancestor of the Roman people. April comes from the Latin verb aperire (to open, as in flower buds). According to Ovid, May came from the Latin words “maiores” (the elders) and June from “juniores” (the younger ones). Months five through ten were named for the numbers – Quintilis, Sextilis, September, October, November, and December.
Twenty-eight centuries ago Numa Pompilius, Rome’s second king, added two months, January and February, to fill in the winter gap. January, appropriately, was named for Janus, the god of beginnings. February is from the Latin word “februum” (purification), honoring a traditional Roman ritual.
Because of superstitions that even numbers are unlucky, this calendar had months with either twenty-nine or thirty-one days, except for February which, inexplicably, had twenty-eight, totaling three hundred and fifty-five. To match the solar calendar, every three or four years, February was truncated and an intercalary month, Mercedonius, inserted between it and March.
When Julius Caesar became consul, he decided to reform this calendar. The modification included insertion of an additional ten days scattered throughout the year, plus an intercalary day added at the end of February every four years. This occurred in AUC 709, (46 BC), seven hundred and nine years after the founding of Rome. AUC stands for “anno urbis conditae”.
Fifteen centuries ago a Scythian monk named Dionysius Exiguus initiated a new frame of reference, the birth of Christ, and in AD 525 published a calendar with the new notation.
A fatal weakness of the Julian calendar was the assumption that a year has precisely three hundred sixty-five and one quarter days. This differs from an actual solar year by about two thirds of a day per century. By the sixteenth century the Julian calendar had fallen ten days behind the actual solar calendar.
Pope Gregory decided to make up the missing ten days and to establish a process that prevented this problem from happening in the future. Consequently, he decreed that October 4, 1582 would be followed by October 15, 1582, a decree that caused much consternation among his followers.
The Pope’s decree also eliminated the possibility of the problem reoccurring in the near future by eliminating leap year each time the year was divisible by one hundred except for those years also divisible by four hundred. Our current calendar (Gregorian) is based on his decree.
In the Jewish calendar, today is the fifteen day of Tishrei, in the year 5781. The Jewish calendar is lunisolar, eleven days shorter than the solar year, with intercalary months added seven times every nineteen years to match the Metonic cycle, a cycle in which the moon’s phases reoccur at nearly the same time in the solar year every nineteenth year. Even this approximation isn’t perfect; the Jewish year is losing one day every two hundred and sixteen years.
The Chinese calendar is also lunisolar. The accepted starting date for the Chinese calendar is the beginning of the reign of the Yellow Emperor, Huangdi, which is believed to have occurred 4719 years ago. Consequently today is the seventeenth day of the eighth month, bayue (the rooster), 4719. The date for Chinese New Year varies as much from year to year as does the one for Rosh Hashanah. It occurs simultaneously with the second new moon after the winter solstice, unless it is a leap year, in which case it is the third new moon.
Logic tells me we are best served by following a solar calendar and knowing with confidence when the seasons change. However, there are also advantages to the lunar calendar. Watching a full moon rise, as I did three days ago, is as big a thrill today as it was the first time I observed it.
And we must not ignore the significance of the lunar cycle on agriculture (and construction). I distinctly remember my Pennsylvania Dutch Aunt Ethel laughing at her neighbor John Benedict when he installed a new fence during a waxing moon and her gloating when the earth “spit it out” and he had to repeat his work. “Even a fool knows you put things in the earth after a full moon”.
The Farmers Almanac does report that geophytes (root vegetables) – potatoes, carrots, onions, etc. – prosper when planted immediately after a full moon. It is easy for us Pennsylvania Dutch civil engineers to see the extension of this to things like fence posts, bridge piers, and building foundations. All things considered, I think I will opt for a solar calendar that clearly has the lunar cycles superposed on it.
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