Traditional Chinese Lunar Calendar
The Traditional Chinese Lunar Calendar is the longest chronological record in history dating back to 2,600 BC, when the Emperor Huang Di (黄帝) introduced the first cycle of the Zodiac.
It is a combination of the solar and lunar calendar, and based on a numerous astronomical calculations. The months begin with a new moon, and the Chinese New Year falls on the second new moon after the Winter Solstice. A complete cycle takes 60 years and is made up of five cycles of 12 years each.
Each of the 12 years is named after a Zodiac Animal. These 12 animals are the Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog and the Boar.
In the Traditional Chinese Lunar Calendar, an Ordinary Year has 12 months, while a Leap Year have 13 months.
Unlike Western (Gregorian) Calendars, where the Leap Year has an additional day (29th February), Leap Years in the Chinese Lunar Calendar have an extra month.
The length of a Lunar Month is the length of time between two New Moons. This cycle averages to about 29.53 days, but can still vary by several hours at any time of the year.
Each month starts on the day of the New Moon, and there are usually 12 months with each month corresponding to one Lunar Cycle.
The number of days in a Lunar Month varies between 29 and 30 days, thus an ordinary year in the Chinese Lunar Calendar has 353, 354 or 355 days.
However, seven times in a 19 year cycle, an extra month ie. Leap Month (闰月 Run Yue) is added. Therefore, in a Leap Year, there are 383, 384 or 385 days.
Leap year occurs when there are 13 New Moons instead of 12 for that particular year.
To determine when these Leap Months are added, we need to look at the Chinese system of Solar Terms. 24 dates, made up of 12 Principle Terms and 12 Sectional Terms, divide the Solar Year into these 24 periods based on the Earth’s position around the Sun.
According to the Chinese system, the Winter Solstice occur in the 11th month of the year. A Lunar Month where a Principle Term does not occur, becomes a Leap Month and is assigned the number of the month before it, but it is still designated as a Leap Month. In the year where this occurs twice, only the first month that this happens is a Leap Month.
Traditionally, the Chinese believes that the Leap Month would follow the 7th Month and the Chinese Lunar New Year starts on the 2nd New Moon after the Winter Solstice.
However, in early 1990s, Chinese Astronomers discovered that there was an error in the Chinese Calendar for the year 2033. You can read about the Error in the Year 2033 Calendar here.
For the Chinese, the years, months and days are assigned a name based upon the Chinese system of Heavenly Stems and Earthly Branches. In this cyclical system, each year, month and day is associated with one of the 10 Heavenly Stems and 12 Earthly Branches. Each successive time period has a new stem and branch until it has gone through the stems 6 times and the branches 5 times, which gives 60 unique combinations.
The 12 months in the Chinese Lunar Calendar are related to Agriculture, and are also named after plants !
- Primens, First month (正月) : Latin “Primus mensis”
- Apricomens, Apricot month (杏月) : Apricot blossoms
- Peacimens, Peach month (桃月) : Peach blossoms
- Plumens, Plum month (梅月) : Plum ripens
- Guavamens, Guava month) (榴月) : Pomegranate blossoms
- Lotumens, Lotus month (荷月) : Lotus blossoms
- Orchimens, Orchid month (蘭月) : Orchid blossoms
- Osmanthumens, Osmanthus month (桂月) : Osmanthus blossoms
- Chrysanthemens, Chrysanthemum month (菊月) : Chrysanthemum blossoms
- Benimens, Good month (良月) : Good month
- Hiemens, Hiemal month (冬月) : Hiemal month
- Lamens, Last month (臘月) : Last month
For calculations of years and dates, this gives a continuous cycle for thousands of years. But in the case of a Leap Month, it is assigned its preceding month’s stem and branch combination with the Leap designation added. Thus calculation for years and days could be easily done, but to find the months, a complicated Astronomical calculation is required.