Before the adoption of the Western solar calendar system, Vietnamese people exclusively followed a lunar calendar in determining the times of planting, harvesting, and festival occasions.
Overview of the Vietnamese Lunar Calendar
Though today, people in Vietnam use the Western calendar for most practical matters of daily life, the old system still serves as the basis for determining numerous seasonal holidays. Vietnamese people have long accepted this coexistence of two calendar systems. As with the Chinese, the Vietnamese lunar calendar begins with the year 2637 B.C. It has 12 months of 29 or 30 days each, and the year totals 355 days.
A lunar month is determined by the period required for the moon to complete its full phasic cycle of 29 and a half days, a standard that makes the lunar year a full 11 days shorter than its solar counterpart. This difference is made up every 19 years by the addition of seven lunar months. The 12 lunar months are further divided into 24 solar divisions distinguished by the four seasons and times of heat and cold, all bearing close relationship to the yearly cycle of agricultural work.
Approximately every third year, an extra month is included between the third and fourth months. This is to reconcile the lunar calendar with the solar one.
Unlike a century of 100 years, the Vietnamese calendar is divided into 60-year periods called “Hoi”. This “Hoi” or 60-year period is divided into two shorter cycles; one of a ten-year cycle and the other of a 12-year cycle.
The ten-cycle, called “Can” is composed of ten heavenly stems. Their names and approximate translations are as follows:
1. Giap – water in nature 2. At – water in the home 3. Binh – lighted fire 4. Dinh – latent fire 5. Mau – wood of all types 6. Ky – wood set to burn 7. Canh – metal of all kinds 8. Tan – wrought metal 9. Nham – virgin land 10. Quy – cultivated land
The 12-year cycle, “Ky”, has 12 earthy stems represented by the names of 12 names in the zodiac. Their names and translations in order are:
1. Ty – the rat 2. Suu – the buffalo 3. Dan – the tiger 4. Mao – the Cat 5. Thin – the dragon 6. Ty – the snake 7. Ngo – the horse 8. Mui – the goat 9. Then – the monkey 10. Dau – the cock (the chicken) 11. Tuat – the dog 12. Hoi – the pig
A Vietnamese year is named after the combination of one of the names of the ten heavenly stems and one of the names of the 12 earthly stems. For instance, 1964 was the Year of the Dragon, “Giap-Thin”. Giap is the first of the ten-year cycle and Thin is the fifth of the 12-year cycle. The year 1965 was “At-Ty”. This follows down the line each year. The ten-year stem is not usually mentioned when discussing the year. Thus, we hear “the Year of Dragon” or “the Year of Snake”, etc. Giap-Thin, the Year of Dragon, will not return for 60 years. This is true of all combinations.
The reasons why Vietnamese people keep using the lunar calendar
Vietnamese people keep using the lunar calendar because they can be sure of a full moon on the 15th day of each month. The lunar calendar can be quite precise and synchronized with the seasons so long as correct astronomical data are used.
Nowadays, Vietnamese people use the solar calendar like other countries in the world to be easy work, but they still keep using the lunar calendar to count the traditional festivals and occasions that are related to the history and culture such as the Tet holiday, Full Moon day, Hung King Death anniversary, etc. The death anniversary of the ancestors is the most important event that all the members of the family must remember. This is the way Vietnamese people express their gratitude and respect to their Vietnamese ancestors. Although when anyone in the family is dead, they would inform everyone in both solar and lunar calendars; they just celebrate the death anniversary in the lunar calendar.
Besides that, the important day of a person’s life is also counted in the lunar calendar such as establishing a new house, getting married, etc. The first day and 15th day of the month in the lunar calendar are very important days for the Vietnamese spirit. In those days, they usually go to temples, and pagodas to pray for luckiness, and happiness as well as buy flowers and fruits to put on the ancestor altar and burn incense to worship their ancestors.
Vietnamese people believe that if you have your hair cut, or break the mirror on the first day of the month in the lunar calendar, you will have bad luck during that month. So, they often avoid doing that stuff. Some foods such as dog meat, and duck meat are not eaten in the first months of the year.
In general, the lunar calendar is a traditional Vietnamese norm that has been used for thousands of years and is still for now. If you want to explore the facts about Vietnamese culture, let’s contact us via the Vietnam travel blog. Thank you!