Post
by drrnwynbchnbrgr » Tue May 20, 2008 2:01 pm
The Chinese calendar is a lunisolar calendar, incorporating elements of a lunar calendar with those of a solar calendar. This measure of time is not exclusive to China, but followed by many other Asian cultures. However, it is often referred to by the Western cultures as the Chinese calendar. In most of Asia today, the Gregorian calendar is used for day to day activities, but the Chinese calendar is still used for marking traditional East Asian holidays such as the Lunar New Year (Spring Festival), and in China the Duan Wu festival, and the Mid-Autumn Festival, and in astrology, such as choosing the most auspicious date for a wedding or the opening of a building. Because each month follows one cycle of the moon, it is also used to determine the phases of the moon.
In China, the traditional calendar is known as the "agricultural calendar" (traditional Chinese: 農曆; simplified Chinese: 农历; pinyin: nónglì) while the Gregorian calendar is known as the "common calendar" (traditional Chinese: 公曆; simplified Chinese: 公历; pinyin: gōnglì) or "Common calendar" . Another name for the Chinese calendar is the "Yin Calendar" (traditional Chinese: 陰曆; simplified Chinese: 阴历; pinyin: yīnlì) in reference to the lunar aspect of the calendar, whereas the Gregorian calendar is the "Yang Calendar" (traditional Chinese: 陽曆; simplified Chinese: 阳历; pinyin: yánglì) in reference to its solar properties. The Chinese calendar was also called the "old calendar" (traditional Chinese: 舊曆; simplified Chinese: 旧历; pinyin: jìulì) after the "new calendar" (traditional Chinese: 新曆; simplified Chinese: 新历; pinyin: xīnlì), i.e. the Gregorian calendar, was adopted as the official calendar. The traditional calendar is also often referred to as "the Xia Calendar", following a comment in the Shiji which states that under the Xia Dynasty, the year began on the second moon after the winter solstice (just as in the modern calendar).
The current year in the Chinese calendar is the Year of the Earth Rat (year of Wù Zǐ, 戊子). It lasts from 7 February 2008 to 25 January 2009. Based on traditional beliefs, some form of the calendar has been in use for almost five millennia. Based on archaeological evidence some form of it has been in use for three and a half millennia.
Early history
The earliest evidence of the Chinese calendar is found on oracle bones of the Shang dynasty (late second millennium BC), which seem to describe a lunisolar year of twelve months, with a possible intercalary thirteenth, or even fourteenth, added empirically to prevent calendar drift. The Sexagenary cycle for recording days was already in use. Tradition holds that, in that era, the year began on the first new moon after the winter solstice.
Early Eastern Zhou texts, such as the Spring and Autumn Annals, provide better understanding of the calendars used in the Zhou dynasty. One year usually had 12 months, which were alternatively 29 and 30 days long (with an additional day added from time to time, to catch up with "drifts" between the calendar and the actual moon cycle), and intercalary months were added in an arbitrary fashion, at the end of the year.
These arbitrary rules on day and month intercalation caused the calendars of each state to be slightly different, at times. Thus, texts like the Annals will often state whether the calendar they use (the calendar of Lu) is in phase with the Royal calendar (used by the Zhou kings).
Although tradition holds that in the Zhou, the year began on the new moon which preceded the winter solstice, the Spring and Autumn Annals seem to indicate that (in Lu at least) the Yin calendar (the calendar used in Shang dynasty, with years beginning on the first new moon after the winter solstice) was in use until the middle of the 7th century, and that the beginning of the year was shifted back one month around 650 BC.
By the beginning of the Warring States, progress in astronomy and mathematics allowed the creation of calculated calendars (where intercalary months and days are set by a rule, and not arbitrarily). The sìfēn 四分 (quarter remainder) calendar, which began about 484 BC, was the first calculated Chinese calendar, so named because it used a solar year of 365¼ days, along with a 19-year (235-month) Rule Cycle, known in the West as the Metonic cycle. The year began on the new moon preceding the winter solstice, and intercalary months were inserted at the end of the year.
In 256 BC, as the last Zhou king ceded his territory to Qin, a new calendar (the Qin calendar) began to be used. It followed the same principles as the Sifen calendar, except the year began one month before (the second new moon before the winter solstice, which now fell in the second month of the year). The Qin calendar was used during the Qin dynasty, and in the beginning of the Western Han dynasty.
[edit] Taichu calendar
The Emperor Wu of the Western Han dynasty introduced reforms that have governed the Chinese calendar ever since. His Tàichū 太初 (Grand Inception) calendar of 104 BC had a year with the winter solstice in the eleventh month and designated as intercalary any calendar month (a month of 29 or 30 whole days) during which the sun does not pass a principal term (that is, remained within the same sign of the zodiac throughout). Because the sun's mean motion was used to calculate the jiéqì (traditional Chinese: 節氣; simplified Chinese: 节气) (or seasonal markings) until 1645, this intercalary month was equally likely to occur after any month of the year. The conjunction of the sun and moon (the astronomical new moon) was calculated using the mean motions of both the sun and moon until 619, the second year of the Tang dynasty, when chronologists began to use true motions modeled using two offset opposing parabolas (with small linear and cubic components). Unfortunately, the parabolas did not meet smoothly at the mean motion, but met with a discontinuity or jump.
[edit] True sun and moon
With the introduction of Western astronomy into China via the Jesuits, the motions of both the sun and moon began to be calculated with sinusoids in the 1645 Shíxiàn calendar (時憲書, Book of the Conformity of Time) of the Qing dynasty, made by the Jesuit Adam Schall. The true motion of the sun was now used to calculate the jiéqì, which caused the intercalary month to often occur after the second through the ninth months, but rarely after the tenth through first months. A few autumn-winter periods have one or two calendar months where the sun enters two signs of the zodiac, interspersed with two or three calendar months where the sun stays within one sign.
Calendar rules
The following rules outline the Chinese calendar since c.104 BC. Note that the rules allow either mean or true motions of the Sun and Moon to be used, depending on the historical period.
1. The months are lunar months. This means the first day of each month beginning at midnight is the day of the astronomical new moon. (Note, however, that a "day" in the Chinese calendar begins at 11 p.m. and not at midnight)
2. Each year has 12 regular months, which are numbered in sequence (1 to 12) and have alternative names. Every second or third year has an intercalary month (閏月 rùnyuè), which may come after any regular month. It has the same number as the preceding regular month, but is designated intercalary.
3. Every other jiéqì of the Chinese solar year is equivalent to an entry of the sun into a sign of the tropical zodiac (a principal term or cusp).
4. The sun always passes the winter solstice (enters Capricorn) during month 11.
5. If there are 12 months between two successive occurrences of month 11, at least one of these 12 months must be a month during which the sun remains within the same zodiac sign throughout (no principal term or cusp occurs within it). If only one such month occurs, it is designated intercalary, but if two such months occur, only the first is designated intercalary.
6. The times of the astronomical new moons and the sun entering a zodiac sign are determined in the Chinese Time Zone by the Purple Mountain Observatory (紫金山天文台 Zǐjīnshān Tiānwéntái) outside Nanjing using modern astronomical equations. Chinese Americans use Nanjing Calendar instead of defining a local one. To them, the new Moon can occur on the last day of the previous month according to their local USA time. For example, A new Moon occurred on May 16, 2007 by USA time, but Chinese Americans still regard May 17, 2007 as the first day of a new month. Further, they define the boundaries of the day according to a USA local time zone. Thus rule number 1 is not followed in this case,.
The zodiac sign which the sun enters during the month and the ecliptic longitude of that entry point usually determine the number of a regular month. Month 1, zhēngyuè, literally means principal month. All other months are literally numbered, second month, third month, etc.