(Editor's Note: This article was originally published on March 20, 2009. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Two times a year, as the Earth revolves in its orbit, its axis reaches a midpoint where neither the North or South Poles are tilted towards the sun. The days when this takes place are called the Vernal (Spring) and Autumnal (Fall) Equinox. The word comes from Latin, meaning "equal night" - that is, when the night is equal to the day. Today in the northern hemisphere, it is the Vernal Equinox, the first day of spring.
While most places today begin their calendar year in January, for many cultures in the past the new year often began in spring, as marked by the Vernal Equinox. Spring, as a time of renewal and the beginning of the agricultural season, seems a very suitable time for beginning another year. The astrological year also begins at the Vernal Equinox, when the sun enters the sign of Aries.
As early civilizations became more complex, they began to perceive the need for formal calendars to regulate annual events, to organize the agriculture year, religious festivals and civic affairs. But almost invariably, these calendars used lunar months to demarcate the year. The passage of the months, from new moon to new moon, is very easy to observe, but unfortunately, the length of a solar year (about 365 days) does not divide evenly into months of about 29 days. Thus with a lunar calendar there will always be days left over at the end of the year, or else the lunar year (usually 354 days) will be shorter than the solar year.
This is not always considered a problem. The Islamic religious calendar has always been a lunar one, with the new year called Al-Hijra, the first day of the month Muharram. But because the Islamic lunar year is shorter than the solar year, it shifts backwards about eleven days every year. In 2009 (1431 in the Islamic calendar), the new year will be December 18. The important religious observances such as Ramadan also take place earlier every year.
In most other civilizations, however, this discrepancy between lunar and solar calendars was a problem with festivals meant to mark annual seasons. Consequently, the priests and astronomers in charge of the calendar had to keep fiddling with it, adding extra days or months to try to keep it coordinated with the solar year. This sort of calendar, incorporating lunar months with a solar year, is called a lunisolar calendar.
The Babylonians, in the first millennium BC, devised a calendar with twelve lunar months and added an extra leap month occasionally to keep the year on track. The Babylonian new year began in the month called Nisannu, in the spring, determined by the Vernal Equinox. But because their lunar month began at the new moon, the date of the new year was not the equinox but the first new moon after it.
In Babylon, the new year was marked by a festival called Akitu that celebrated the beginning of creation, when the supreme god Marduk defeated the monster of chaos, Tiamat. At this spring festival, which lasted several days, the epic of the creation was recited. In addition, the king was ceremonially de-throned and required to submit himself to Marduk before being reinstated.
The astronomers of Babylon were considered the most knowledgeable, and other Mesopotamian nations followed the Babylonian calendar. The Assyrians celebrated much the same Akitu ceremony, substituting their own supreme god Ashur for Marduk.
Some people insist that the Vernal Equinox in Mesopotamia also marked the rebirth of the god Tammuz. This was a very ancient god, originally known in Sumeria as Dumuzi, where he may have been a shepherd god. He became a god of vegetation, finally a god of the underworld who died and rose again from the dead. The same fundamental story was also told of other deities worshiped in other cultures, notably Adonis, Attis, and Persephone. However, the resurrection of this god was not always celebrated in the spring, and not always at the equinox. The rites mourning his death were usually at the height of summer's heat, and the renewal of the vegetation came with the autumn rains in the Mediterranean climate.
The Persians retained the basic form of the Babylonian calendar but later modified it to a 360 day year, with five extra days added. The Persian astronomers, known as Magi, were even more skilled than the Babylonians. Persians belonged to a different ethnic group than the Babylonians, with a different religion that centered around a god of truth and light, thus making them prefer a solar calendar to a lunar one. In their language, the new year's festival was named Nowruz, and it began on sunrise of the Vernal Equinox. This festival is said to commemorate the legendary king Jamshid, who saved the world from winter. Other sources say that it marked the creation of the universe, much as the Babylonian myth did. Nowruz is still celebrated by Zoroastrians, by the Parsis in India, by Kurds, and by members of the Ba'hai faith.
The Babylonian calendar was also adopted by the Israelites, who kept the same name of the first month of the year, calling it Nisan. As in the Babylonian calendar, the month began with the new moon after the Vernal Equinox, but the calculation was complicated by the annual spring sacrifice of a lamb called Pesach, now known in English as Passover. This sacrifice, on the fifteenth day of the month, could not take place before the equinox, as the scripture dictated: "Guard the month of spring, and make then the Pesach offering." ( Deuteronomy 16:1) Thus the priests were sometimes required to add a leap month before Nisan in order to ensure that Pesach would always take place in the spring.
While Nisan was thus the first month of the religious ceremonial year for the Israelites, the Feast of Trumpets (Rosh Hashanah) in the fall later became the beginning of the civil year. It has not been uncommon for some nations to establish more than one year cycle for different purposes, just as we have a fiscal year for accounting purposes today.
Because the Christian festival known in English as Easter is based on the Pesach feast, the early Christian liturgical calendar at first followed the Jewish one in the calculation of the Paschal date. However, because the date is required to fall on a Sunday after the vernal equinox, the computations varied somewhat from those that calculated the date of Pesach, and this became a contentious issue among the various early Christian sects.
For the most part, the Christian calendar followed the Roman one, after it was reformed by Julius Caesar. Originally, the Roman new year began in the month of the Vernal Equinox, called Martius (March). It is notable that in astrology, the constellation Aries is rules by the planet Mars. But this early calendar was very complicated, confusing and inaccurate. There were at first only ten months, with many days left out at the end of the year. Later, two more months, Januarius and Februarius, were added at the end to make 355 days, with a leap month as necessary, when the Roman priests got around to adding it.
In 153 BC, the beginning of the civil year was changed to the first of Januarius, so it no longer began in spring. And in 46 BC, Julius Caesar made a complete reform of the Roman calendar to a solar cycle of 365 days in a normal year and a leap year of 366 days. This Julian calendar was adopted throughout the Roman world.
However, after the Roman Empire fell, the Christian churches in many places wanted to begin their new liturgical years on the dates of important religious celebrations, such as Christmas on December 25 or Lady Day on March 25, one of the Quarter Days that marked the beginning of spring, and which was originally on the Vernal Equinox. Thus for example in England, there were two new years, one on January 1 and the other on March 25. This did not change until 1752, with the adoption of the Gregorian calendar, which is generally in use today, although some eastern Christian churches still use a Julian liturgical calendar, with the result that they celebrate Easter on a different date than those that use the Gregorian.
In 2009, the Vernal Equinox is today, March 20. The date of Passover will be April 9, the western Easter April 12, and the eastern Easter a week later on April 19. Happy New Year to all!
Photo Credits: Nowruz photo by Reza Nazarbeygi http://creativecommons.org/licenses/by-sa/2.5/