The Jewish Calendar
contains 12 lunar months. In every 19-year cycle there are seven leap years, in which an extra month is inserted, so that the spring equinox always falls in the month Nisan, when the Passover is celebrated. Thus the Jewish calendar is adjusted to the solar year. In the Jewish calendar, years are counted from the date on which, according to Jewish tradition, the universe was created. It corresponds to 3761 B.C.
The Church Calendar
refers to the schedule used by the Christian church in indicating events and seasons of the liturgical year. In the Roman Catholic, Anglican, and Protestant churches, the year begins with the Advent season, the four weeks preceding Christmas. Other seasons include Epiphany, Lent, Easter, and Pentecost. The Eastern Orthodox church divides the liturgical year into three partstriodion (the 10 weeks before Easter), pentecostarion (the SO days after Easter), and octoechos (the rest of the year).
The Muslim Calendar
is the only true lunar calendar in everyday use. It consists of a year of 12 lunar months. In every 30-year period there are 19 years of 354 days and 11 leap years of 355 days. (The extra days are needed to make each month begin with a new moon.) Muslims date their calendar from the Hegira, Mohammed's flight to Medina in 622 A.D.
The French Calendar
The French National Convention established a new calendar for France in November of 1793, during the Revolution. The year was divided into 12 months of 30 days each, with five days of merrymaking at the end of each year. The new calendar was dated back to September 22, 1792, when the new republic took form. It was observed until Napoleon abolished it as of January 1, 1806. The Gregorian calendar was then resumed.
The Chinese Calendar
The Chinese calendar uses both lunar and solar dating systems. It is used today primarily to determine the dates of Chinese festivals.
The Chinese year consists of 12 lunar months, alternating between months of 29 and 30 days. The year is 354 days long, or about 12 lunar cycles. An extra, or intercalary, month is added to the lunar year seven times every 19 years to reconcile it with the solar (365-day) year. Each lunar year is named for one of a series of 12 animals.
The Chinese calendar does not count years in a continuous manner. It uses a 60-year cycle and a system of regional years that begin with each emperor. Chinese tradition holds that the first year of the Yellow Emperor was 2637 B.C.E. (before the common era), and that the emperor introduced a counting system based on this date. The calendar is dated from the middle years of the Shang dynasty (about 1300 B.C.).