"Why does lunar New Year never seem to fall on January 1?" "How does the lunar year differ from a solar year?" Welcome to the world of the lunar calendar, and the astonishingly gifted ancient Chinese who first put it together.
People in Taiwan, China, and some neighboring countries such as Japan use a lunar dating system concurrently with the Western Gregorian calendar. Each lunar year consists of twelve months of alternately twenty-nine and thirty days, totaling 354 days for roughly twelve full lunar cycles. So-called "intercalary months" are inserted when required to keep the lunar year in step with the solar 365-day year. Generally speaking, the lunar date falls about one month behind the solar one.
By the fourteenth century B.C., the Shang Dynasty (1766-1122 B.C.) had established the solar year at 365.25 days, and lunation (the time that elapses between successive full moons) at 29.5 days. One of the two methods they used to create this calendar was to add an extra month of twenty-nine or thirty days, which they termed the thirteenth month, to the end of a regular twelve-month year.
There is also evidence to suggest that by no later than the Spring and Autumn Period (770-476 B.C.) the Chinese had developed a complex cycle of nineteen years containing 235 months, of which seven were intercalations. The other method involved inserting an extra month between any two months of a regular year. This system, however, was abandoned fairly quickly.
By the third century B.C., the first method of intercalation was starting to fall from favor, to be replaced by the establish ment of a meteorological cycle that contained twenty-four "points," each introducing a certain period of time, with romantic -sounding names such as Rain Water, Excited Insects, Summer Solstice, and Hoar Frost Descends. These points, called chieh chi in Mandarin, originated in ancient China's fertile Yellow River valley, and they describe climactic changes that have always been important to farmers. The formulation of this cycle must have required elaborate instruments and considerable astronomical knowledge. The superiority of Chinese astronomy, at least until about the thirteenth century A.D., is now widely acknowledged.
The twenty-four chieh chi coincide with points fifteen degrees apart on the ecliptic (a complete circle of 360 degrees). It takes about 15.2 days for the sun to travel from one of these points to another, or 364.8 days to complete the circuit, while the Earth needs 365.25 days to circle the sun. Supposedly, each of the twelve months of the year contains two chieh chi; however, because a lunar month averages only 29.5 days, whereas it generally takes about 30.4 days for the sun to cover the distance demarcated by any three consecutive chieh chi , there is always a chance that a particular lunar month will contain only one of the anticipated "points." Whenever that occurs, an extra month is inserted, and the lunar calendar for that year ends with, say, two Mays or two Julys. These intercalations have acquired something of a sinister reputation, over the years. For example, the title of Cheng Lang-ping's bestseller "Leap" August 1995: China's Violent Invasion of Taiwan , which designated 1995 through 1998 as a window of opportunity for the mainland to attack and invade Taiwan, plays on that phenomenon.
A complete meteorological cycle makes up one solar year, so the Chinese calendar is basically a combination of lunar and solar systems, sometimes called the yin yang li (li means "calendar"). "[The chieh chi fall on] six and twenty-one [of the month] in the first half of the year, eight and twenty-three in the second, or only one or two days ahead or after": thus runs an old saw that marks the correspondence between the meteorological cycle and the solar calendar. For example, in 1999 "Spring Begins" fell on February 4, "Summer Solstice" on June 22, and "Autumn Begins" on August 8.
Foreign calendars were brought to China quite early on. Examples are the Hindu calendar in the Tang Dynasty (A.D. 618-907) and the Muslim calendar in the thirteenth century. The Gregorian calendar was taken to China by Jesuit missionar ies toward the end of the sixteenth century. In 1912, the republican government officially replaced the lunar calendar with the Gregorian calendar, but despite that, Chinese people throughout the world continue to observe holidays in accordance with the lunar calendar. Today, the Western New Year means a day off work, but the real celebrations commence a couple of weeks later.