Lunisolar calendar

A lunisolar calendar is a calendar in many cultures whose date indicates both the Moon phase and the time of the solar year. If the solar year is defined as a tropical year, then a lunisolar calendar will give an indication of the season; if it is taken as a sidereal year, then the calendar will predict the constellation near which the full moon may occur. As with all calendars which divide the year into months there is an additional requirement that the year have a whole number of months. In this case ordinary years consist of twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month.


The Hebrew, Jain, Buddhist, Hindu and Kurdish as well as the traditional Burmese, Chinese, Japanese, Tibetan, Vietnamese, Mongolian and Korean calendars (in the east Asian cultural sphere), plus the ancient Hellenic, Coligny, and Babylonian calendars are all lunisolar. Also, some of the ancient pre-Islamic calendars in south Arabia followed a lunisolar system.[1] The Chinese, Coligny and Hebrew[2] lunisolar calendars track more or less the tropical year whereas the Buddhist and Hindu lunisolar calendars track the sidereal year. Therefore, the first three give an idea of the seasons whereas the last two give an idea of the position among the constellations of the full moon. The Tibetan calendar was influenced by both the Chinese and Buddhist calendars. The Germanic peoples also used a lunisolar calendar before their conversion to Christianity.

The Islamic calendar is lunar, but not a lunisolar calendar because its date is not related to the Sun. The civil versions of the Julian and Gregorian calendars are solar, because their dates do not indicate the Moon phase — however, both the Gregorian and Julian calendars include undated lunar calendars that allow them to calculate the Christian celebration of Easter, so both are lunisolar calendars in that respect.

Determining leap months

A rough idea of the frequency of the intercalary or leap month in all lunisolar calendars can be obtained by the following calculation, using approximate lengths of months and years in days:

  • Year: 365.25, Month: 29.53
  • 365.25/(12 × 29.53) = 1.0307
  • 1/0.0307 = 32.57 common months between leap months
  • 32.57/12 = 2.7 common years between leap years

Intercalation of leap months is frequently controlled by the "epact", which is the difference between the lunar and solar years (approximately 11 days). The Metonic cycle, used in the Hebrew calendar and the Julian and Gregorian ecclesiastical calendars, adds seven months during every nineteen-year period. The classic Metonic cycle can be reproduced by assigning an initial epact value of 1 to the last year of the cycle and incrementing by 11 each year. Between the last year of one cycle and the first year of the next the increment is 12. This adjustment, the saltus lunae, causes the epacts to repeat every 19 years. When the epact goes above 29 an intercalary month is added and 30 is subtracted. The intercalary years are numbers 3, 6, 8, 11, 14, 17 and 19. Both the Hebrew calendar and the Julian calendar use this sequence.

The Buddhist and Hebrew calendars restrict the leap month to a single month of the year; the number of common months between leap months is, therefore, usually 36, but occasionally only 24 months. Because the Chinese and Hindu lunisolar calendars allow the leap month to occur after or before (respectively) any month but use the true motion of the Sun, their leap months do not usually occur within a couple of months of perihelion, when the apparent speed of the Sun along the ecliptic is fastest (now about 3 January). This increases the usual number of common months between leap months to roughly 34 months when a doublet of common years occurs, while reducing the number to about 29 months when only a common singleton occurs.

With uncounted time

An alternative way of dealing with the fact that a solar year does not contain an integer number of months is by including uncounted time in the year that does not belong to any month. Some Coast Salish peoples used a calendar of this kind. For instance, the Chehalis began their count of lunar months from the arrival of spawning chinook salmon (in Gregorian calendar October), and counted 10 months, leaving an uncounted period until the next chinook salmon run.[3]

Gregorian lunisolar calendar

The Gregorian calendar has a lunisolar calendar, which is used to determine the date of Easter. The rules are in the Computus.

List of lunisolar calendars

The following is a list of lunisolar calendars:

See also


  1. ^ F.C. De Blois, "TAʾRĪKH": I.1.iv. "Pre-Islamic and agricultural calendars of the Arabian peninsula", The Encyclopaedia of Islam, 2nd edition, X:260.
  2. ^ The modern Hebrew calendar, since it is based on rules rather than observations, does not exactly track the tropical year, and in fact the average Hebrew year of ~365.2468 days is intermediate between the tropical year (~365.2422 days) and the sidereal year (~365.2564 days).
  3. ^ Suttles, Wayne P. Musqueam Reference Grammar, UBC Press, 2004, p. 517.


  • Dershowitz, Nachum; Reingold, Edward M. (2008), Calendrical Calculations, Cambridge: Cambridge University Press, ISBN 9780521885409

External links

Buddhist calendar

The Buddhist calendar is a set of lunisolar calendars primarily used in mainland Southeast Asian countries of Cambodia, Laos, Myanmar and Thailand as well as in Sri Lanka and Chinese populations of Malaysia and Singapore for religious or official occasions. While the calendars share a common lineage, they also have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a year numbering system shared by the traditional Thai lunisolar calendar and by the Thai solar calendar.

The Southeast Asian lunisolar calendars are largely based on an older version of the Hindu calendar, which uses the sidereal year as the solar year. One major difference is that the Southeast Asian systems, unlike their Indian cousins, do not use apparent reckoning to stay in sync with the sidereal year. Instead, they employ their versions of the Metonic cycle. However, since the Metonic cycle is not very accurate for sidereal years, the Southeast Asian calendar is slowly drifting out of sync with the sidereal, approximately one day every 100 years. Yet no coordinated structural reforms of the lunisolar calendar have been undertaken.

Today, the traditional Buddhist lunisolar calendar is used mainly for Theravada Buddhist festivals, and no longer has the official calendar status anywhere. The Thai Buddhist Era, a renumbered Gregorian calendar, is the official calendar in Thailand.

Chinese calendar

The traditional China calendar (officially known as the Rural Calendar [農曆; 农历; Nónglì; 'farming calendar']), or Former Calendar (舊曆; 旧历; Jiùlì), Traditional Calendar (老曆; 老历; Lǎolì) or Lunar Calendar (陰曆; 阴历; Yīnlì; 'yin calendar'), is a lunisolar calendar which reckons years, months and days according to astronomical phenomena. It is defined by GB/T 33661-2017, "Calculation and promulgation of the Chinese calendar", issued by the Standardisation Administration of China on 12 May 2017.

Although modern day China uses the Gregorian calendar, the traditional Chinese calendar governs holidays (such as the Chinese New Year) in China and in overseas Chinese communities. It lists the dates of traditional Chinese holidays and guides people in selecting auspicious days for weddings, funerals, moving, or starting a business.

Like Chinese characters, variants of this calendar are used in different parts of the Chinese cultural sphere. Korea, Vietnam, and the Ryukyu Islands adopted the calendar, and it evolved into Korean, Vietnamese, and Ryukyuan calendars. The main difference from the traditional Chinese calendar is the use of different meridians, which leads to some astronomical events—and calendar events based on them—falling on different dates. The traditional Japanese calendar also derived from the Chinese calendar (based on a Japanese meridian), but its official use in Japan was abolished in 1873 as part of reforms after the Meiji Restoration. Calendars in Mongolia and Tibet have absorbed elements of the traditional Chinese calendar, but are not direct descendants of it.Days begin and end at midnight, and months begin on the day of the new moon. Years begin on the second (or third) new moon after the winter solstice. Solar terms govern the beginning and end of each month. Written versions in ancient China included stems and branches of the year and the names of each month, including leap months as needed. Characters indicated whether a month was long (大, 30 days) or short (小, 29 days); stem branches for the first, eleventh, and 21st days, and the date, stem branch and time of the solar terms.

Genka calendar

The Genka calendar (元嘉暦, Genka-reki), also known as Yuan-chia li, was a Japanese lunisolar calendar (genka reki). It was used from 604 to 680.

Gihō calendar

The Gihō calendar (儀鳳暦, Gihō-reki), also known as Yi-feng li, was a Japanese lunisolar calendar (genka reki).

Goki calendar

The Goki calendar (五紀暦, Goki-reki), also known as Wuji li, was a Japanese lunisolar calendar (genka reki). It was developed in China; and it was used in Japan in the mid-9th century.

Hōryaku calendar

The Hōryaku calendar (宝暦暦, Hōryaku-reki) was a Japanese lunisolar calendar (genka reki). It was also known as Hōryaku Kōjutsu Gen-reki (宝暦甲戌元暦). It was published in 1755.

Jōkyō calendar

The Jōkyō calendar (貞享暦, Jōkyō-reki) was a Japanese lunisolar calendar, in use from 1684 to 1753. It was officially adopted in 1685.

Kansei calendar

Kansei calendar (寛政暦, Kansei-reki) was a Japanese lunisolar calendar (genka reki). It was published in 1797.

Korean calendar

The traditional Korean calendar is a lunisolar calendar. Like most traditional calendars of other East Asian countries, the Korean Calendar is mainly derived from the Chinese calendar. Dates are calculated from Korea's meridian (135th meridian east in modern time for South Korea), and observances and festivals are based in Korean culture.

The Gregorian calendar was officially adopted in 1896, but traditional holidays and age-reckoning for older generations are still based on the old calendar. The biggest festival in Korea today is Seollal, the first day of the traditional Korean New Year. Other important festivals include Daeboreum also referred to as Boreumdaal (the first full moon), Dano (spring festival) and Chuseok (harvest moon festival), and Samjinnal (spring-opening festival). Other minor festivals include Yudu (summer festival), and Chilseok (monsoon festival).

List of festivals in Indonesia

Below is a list of festivals in Indonesia. The list is divided based on their respective calendar.

Lunar New Year

Lunar New Year is the beginning of a calendar year whose months are coordinated by the cycles of the moon. The relevant calendar may be a purely lunar calendar or a lunisolar calendar.

Lunar calendar

A lunar calendar is a calendar based upon the monthly cycles of the Moon's phases (synodic months), in contrast to solar calendars, whose annual cycles are based only directly upon the solar year. The most commonly used calendar, the Gregorian calendar, is a solar calendar system that originally evolved out of a lunar calendar system. A purely lunar calendar is also distinguished from a lunisolar calendar, whose lunar months are brought into alignment with the solar year through some process of intercalation. The details of when months begin varies from calendar to calendar, with some using new, full, or crescent moons and others employing detailed calculations.

Since each lunation is approximately ​29 1⁄2 days (29 days, 12 hours, 44 minutes, 3 seconds, or 29.530588 days), it is common for the months of a lunar calendar to alternate between 29 and 30 days. Since the period of twelve such lunations, a lunar year, is only 354 days, 8 hours, 48 minutes, 34 seconds (354.367056 days), purely lunar calendars lose around 11 days per year relative to the Gregorian calendar. In purely lunar calendars like the Islamic calendar, the lack of intercalation causes the lunar months to cycle through all the seasons of the Gregorian year over the course of a 33 lunar-year cycle.

Although the Gregorian calendar is in common and legal use in most countries, traditional lunar and lunisolar calendars continue to be used throughout the Old World to determine religious festivals and national holidays. Examples of such holidays include Ramadan (Islamic calendar); Easter; the Chinese, Japanese, Korean, Vietnamese, and Mongolian New Year (Chinese, Japanese, Korean, Vietnamese, and Mongolian calendars); the Nepali New Year (Nepali calendar); the Mid-Autumn Festival and Chuseok (Chinese and Korean calendars); Loi Krathong (Thai calendar); Sunuwar calendar; Vesak/Buddha's Birthday (Buddhist calendar); Diwali (Hindu calendars); and Rosh Hashanah (Hebrew calendar).


Mikaribaba (箕借り婆) is a yōkai of a one-eyed old woman in stories and customs of the Kantō region.

Mongolian calendar

The traditional Mongol calendar (Mongolian: цаглабар, Tsaglabar or цаг тооны бичиг, Tsag toony bichig) is a lunisolar calendar based on Tegus Buyantu zurkhai system developed in 1747 by monk Ishbaljir (Сүмбэ хамбо Ишбалжир, Sümbe khambo Ishbaljir; 1704–1788). The Mongol year is composed of either 12 or 13 lunar months, each beginning and ending with a new moon. A thirteenth month is added every two or three years, so that an average year is equal to the solar year.

The Mongol new year celebration is Tsagaan Sar which is celebrated two months after the first new moon following the winter solstice.

In modern Mongolia, the Gregorian calendar is used, with the traditional calendar only used for traditional celebrations and events based on it.

The European system of chronology is called Аргын тоолол (Argyn Toolol, chronology of method) and the Mongol system of chronology is called Билгийн тоолол (Bilgiin Toolol, chronology of wisdom).

Pana Sankranti

Pana Sankranti, (Odia: ପଣା ସଂକ୍ରାନ୍ତି) also known as Maha Vishub Sankranti, is the traditional new year day festival of Buddhists and Hindus in Odisha, India. The festival date is set with the solar cycle of the lunisolar calendar, as the first day of the traditional solar month of Mesha. This is identical to the purnimanta system of lunar month Baisakh (on Indian national system, it is the 24th day of Chaitra). It therefore almost always falls on 14 April every year on the Gregorian calendar.The festival is celebrated with visits to Shiva, Shakti, or Hanuman temples, as the day is considered to be the birthday of Hanuman. People take baths in rivers or major pilgrimage centers. Communities participate in mela (fairs), watch street dance or acrobatic performances. A notable climax of the social celebrations is fire-walk, where volunteers sprint over a bed of burning coal while being cheered with music and songs. Feasts and special drinks such as a chilled sweet mango-milk-yoghurt-coconut drink called Pana is shared, a tradition that partly is the source of this festival's name.Pana Sankranti is similar to new year festivals observed by Hindus elsewhere such as Vaisakhi (north and central India), Bihu (Assam), Pohela Boishakh (Bengal) and Puthandu (Tamil Nadu).

Rapa Nui calendar

The Rapa Nui calendar was the indigenous lunisolar calendar of Easter Island. It is now obsolete.


Tanabata (Japanese: たなばた or 七夕, meaning "Evening of the seventh"), also known as the Star Festival, is a Japanese festival originating from the Chinese Qixi Festival. It celebrates the meeting of the deities Orihime and Hikoboshi (represented by the stars Vega and Altair respectively). According to legend, the Milky Way separates these lovers, and they are allowed to meet only once a year on the seventh day of the seventh lunar month of the lunisolar calendar. The date of Tanabata varies by region of the country, but the first festivities begin on 7 July of the Gregorian calendar. The celebration is held at various days between July and August.

Tenpō calendar

The Tenpō calendar (天保暦, Tenpō-reki), officially the Tenpō sexagenary unitary calendar (天保壬寅元暦 Tenpō jin'in genreki), was a Japanese lunisolar calendar. It was published in the Tenpō era (1830–1844) and was in use during the late Edo period, from 1844 to 1872.

Vietnamese calendar

The Vietnamese calendar is a lunisolar calendar that is based on the Geogorian calendar. As Vietnam's official calendar has been the Gregorian calendar since 1954, the Vietnamese calendar is used mainly to observe lunisolar holidays and commemorations, such as Tết and Mid-Autumn Festival.

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