The Chinese calendar’s origins can be traced as far back as the 14th century B.C.E. It is believed that the calendar was invented by the Emperor Huangdi around 2637 B.C.E. The Chinese calendar is lunisolar and it is based on exact astronomical observations of the sun’s longitude and the moon’s phases. This means that principles of modern science have had an impact on the Chinese calendar.
The Gregorian calendar is used in China for civil purposes in modern times although the Chinese calendar originated from China. However, the Chinese calendar is still used among various Chinese communities around the world. It is used to determine festival dates, such as Chinese New Year, as well as auspicious dates, such as wedding dates. It is also used to determine moon phases because it follows the moon.
What does the Chinese Year look like?
The Chinese calendar is like the Hebrew calendar, which is a combined lunar calendar in that it strives to have its years coincide with the tropical year and its months coincide with the synodic months. Having a few similarities between the Chinese and Hebrew calendar is not really surprising:
- An ordinary year has 12 months, while a leap year has 13 months.
- An ordinary year has 353 to 355 days, while a leap year has 383 to 385 days.
A number of astronomical calculations must be made when determining what the Chinese Year looks like.
First, determine the dates for the new moons. A new moon is a moon where it is in conjunction with the sun, it looks completely “black” and not the first visible crescent used in the Islamic and Hebrew calendars. The date of a new moon is the first day of a new month.
Second, determine the dates when the sun’s longitude is a multiple of 30 degrees. These dates, which are called the “Principle Terms”, are used to determine the number of each month:
||Occurs when the Sun's longitude is
Each month carries the number of principle terms that occurs in that month. A month may contain two principle terms in rare cases; the month numbers may have to be shifted in this case. Principle term 11 must always fall in the 11th month.
All the astronomical calculations are carried out for the meridian 120 degrees east of Greenwich, which roughly corresponds to the east coast of China. In various Chinese communities, some variations in this rules are seen.
What are Leap Years?
The Chinese calendar features 12 months. However, an extra month is inserted in the calendar when a leap year occurs. Thus, leap years in the Chinese calendar have 13 months, unlike leap years in the Gregorian calendar in which an extra day is included. About once every three years, a leap month is added to the Chinese calendar. The name of the leap month is the same as the previous lunar month. A leap year in the Chinese calendar does not necessarily fall at the same time a leap year occurs in the Gregorian calendar.
To figure out if a year is a leap year, the number of new moons between the 11th month in one year, which is the month with the December solstice and the 11th month in the following year must be calculated. The leap year must be inserted if there are 13 new moons from the start of the 11th month in the first year to the start of the 11th month in the second year. At least one month does not contain a principle term in leap years. The solar term years has 12 principle terms to indicate the sun’s longitudes at every 30 degrees. The first month that does not have a principle term is determined as the leap month.
Counting the years and the 60-year cycle
The Chinese calendar does not count years in an infinite sequence, unlike most other calendars. Instead, each year is assigned a name consisting of two components within the 60-year cycle. The first component is the Celestial Stemm.
1. Jia 6. Ji
2. Yi 7. Geng
3. Bing 8. Xin
4. Ding 9. Ren
5. Wu 10. Gui
The second component is a terrestrial branch. It features the names of animals in a zodiac cycle consisting of 12 animals listed below:
1. Zi (rat) 6. Si (snake) 11. Xu (dog)
2. Chou (ox) 7. Wu (horse) 12. Hai (pig)
3. Yin (tiger) 8. Wei (sheep)
4. Mao (rabbit) 9. Shen (monkey)
5. Chen (dragon) 10. You (rooster)
Each of the two components is used sequentially. Thus, the first year of the 60-year cycle becomes jia-zi, the second year is yi-chou, and so on. When the end of a component is reached, one starts from the beginning. The 10th year is gui-you, the 11th year is jia-xu, the 12th year is yi-hai, and the 13th year is bing-zi. Finally, the 60th year is gui-hai.
This pattern of naming years within a 60-year cycle dates back to about 2000 years. A similar naming of days and months is no longer used but the date name is still listed in calendars. It has been customary to number the 60-year cycle since 2637 B.C.E., when the calendar was supposedly invented.
When did the calendar really start?
Why is the current year 60 years too late if the Chinese calendar started in 2637 B.C.E?
The Chinese calendar does not use a continuous year count. They used a 60-year cycle and a system of regional years. Sun Yat-sen wanted to establish a republican alternative to the imperial reign cycles before the 1911 resolution. The first year of the Yellow Emperor was 2698 B.C.E., so he introduced a counting system based on this according to Chinese tradition. Under this system, 2000 is the year 4698. An alternative system is to start with the first historical record of the 60-day cycle from March 8, 2637 B.C.E. 2000 is the year 4637 based on this system.
The Shang oracle bones give evidence of the lunisolar calendar which has been much modified but persists to this day. As said, it is believed that the Emperor Huangdi introduced the calendar around 2637 B.C.E. It is also thought that his minister Ta Nao prepared the first calendar, which is called the Chia-tzu or Kan-chih system.
Another phase was added to the calendar as the system was meant to be for popular use. During the Chou period, 12 animals were associated with each year. These 12 animals were commonly called the 12 zodiac animals in western society. They were said to be merely popular symbols and did not have any great significance. There have been, however, various folktales linked the origin of the 12 animals.