A lunar calendar is a
calendar based on the
monthly cycles of the
Moon's
phases (
synodic months,
lunations), in contrast to
solar calendars, whose annual cycles are based only directly on the
solar year. The most commonly used calendar, the
Gregorian calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years d ...
, 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
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in ...
, whose
lunar months are brought into alignment with the solar year through some process of
intercalation. The details of when months begin vary from calendar to calendar, with some using
new
New is an adjective referring to something recently made, discovered, or created.
New or NEW may refer to:
Music
* New, singer of K-pop group The Boyz
Albums and EPs
* ''New'' (album), by Paul McCartney, 2013
* ''New'' (EP), by Regurgitator, ...
,
full, or
crescent moons and others employing detailed calculations.
Since each lunation is approximately days,
[ (which gives a mean synodic month as 29.53059 days or 29 days 12 hours 44 minutes and 3 seconds)] it is common for the months of a lunar calendar to alternate between 29 and 30 days. Since the period of 12 such lunations, a lunar year, is 354 days, 8 hours, 48 minutes, 34 seconds (354.36707 days),
purely lunar calendars are 11 to 12 days shorter than the
solar year. In purely lunar calendars, which do not make use of intercalation, like the
Islamic calendar
The Hijri calendar ( ar, ٱلتَّقْوِيم ٱلْهِجْرِيّ, translit=al-taqwīm al-hijrī), also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 ...
, the lunar months cycle through all the seasons of a solar year over the course of a
33–34 lunar-year cycle.
Although the
Gregorian calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years d ...
is in common and
legal use in most countries, traditional lunar and lunisolar calendars continue to be used throughout the world to determine
religious festivals and
national holidays. Such holidays include
Rosh Hashanah (
Hebrew calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel ...
);
Easter
Easter,Traditional names for the feast in English are "Easter Day", as in the '' Book of Common Prayer''; "Easter Sunday", used by James Ussher''The Whole Works of the Most Rev. James Ussher, Volume 4'') and Samuel Pepys''The Diary of Samue ...
(the
Computus); the
Chinese,
Korean,
Vietnamese, and
Mongolian New Year (
Chinese,
Korean,
Vietnamese, and
Mongolian calendars, respectively); the
Nepali New Year
Nepal Sambat, also spelled as Nepala Sambata, (Nepal Bhasa: , Nepali: ) is the lunisolar calendar used by the Newari people of Nepal. The Calendar era began on 20 October 879 AD, with 1142 in Nepal Sambat corresponding to the year 2021–2022 ...
(
Nepali calendar Nepali calendar can refer to:
* Vikram Samvat, the official calendar in Nepal
* Nepal Sambat
Nepal Sambat, also spelled as Nepala Sambata, (Nepal Bhasa: , Nepali: ) is the lunisolar calendar used by the Newari people of Nepal. The Calendar era ...
); the
Mid-Autumn Festival and
Chuseok (
Chinese and
Korean calendars);
Loi Krathong (
Thai calendar
In Thailand, two main calendar systems are used alongside each other: the Thai solar calendar, based on the Gregorian calendar and used for official and most day-to-day purposes, and the Thai lunar calendar (a version of the Buddhist calendar, ...
); the
Bengali New Year and
Durga Puja (
Bengali calendar);
Sunuwar calendar;
Vesak/
Buddha's Birthday (
Buddhist calendar
The Buddhist calendar is a set of lunisolar calendars primarily used in Cambodia, Laos, Myanmar, India, Sri Lanka, and Thailand as well as in Malaysia, Singapore and Vietnam by Chinese populations for religious or official occasions. W ...
);
Diwali (
Hindu calendar
The Hindu calendar, Panchanga () or Panjika is one of various lunisolar calendars that are traditionally used in the Indian subcontinent and Southeast Asia, with further regional variations for social and Hindu religious purposes. They adopt ...
s);
Ramadan,
Eid al-Fitr and
Eid al-Adha (
Islamic calendar
The Hijri calendar ( ar, ٱلتَّقْوِيم ٱلْهِجْرِيّ, translit=al-taqwīm al-hijrī), also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 ...
).
The
Japanese Calendar
Japanese calendar types have included a range of official and unofficial systems. At present, Japan uses the Gregorian calendar together with year designations stating the year of the reign of the current Emperor. The written form starts with t ...
formerly used both the lunar and lunisolar calendar before it was replaced by the Gregorian Calendar during the Meiji government in 1872. Holidays such as the
Japanese New Year were simply transposed on top as opposed to being calculated like other countries that use the lunisolar and Gregorian calendars together, for example the Japanese New Year now falls on January 1, creating a month delay as opposed to other East Asian Countries. See
customary issues in modern Japan.
History
A lunisolar calendar was found at
Warren Field in
Scotland
Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...
and has been dated to , during the
Mesolithic period. Some scholars argue for lunar calendars still earlier—
Rappenglück in the marks on a year-old
cave painting at
Lascaux
Lascaux ( , ; french: Grotte de Lascaux , "Lascaux Cave") is a network of caves near the village of Montignac, in the department of Dordogne in southwestern France. Over 600 parietal wall paintings cover the interior walls and ceilings of t ...
and
Marshack in the marks on a year-old bone baton—but their findings remain controversial. Scholars have argued that ancient hunters conducted regular astronomical observations of the Moon back in the
Upper Palaeolithic. Samuel L. Macey dates the earliest uses of the Moon as a time-measuring device back to 28,000–30,000 years ago.
Lunisolar calendars
Most calendars referred to as "lunar" calendars are in fact
lunisolar calendar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in ...
s. Their months are based on observations of the lunar cycle, with
intercalation being used to bring them into general agreement with the solar year. The solar "
civic calendar" that was used in
ancient Egypt showed traces of its origin in the earlier lunar calendar, which continued to be used alongside it for religious and agricultural purposes. Present-day lunisolar calendars include the
Chinese,
Vietnamese,
Hindu
Hindus (; ) are people who religiously adhere to Hinduism. Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for ...
,
Hebrew and
Thai calendars.
Synodic months are 29 or 30 days in length, making a
lunar year of 12 months about 11 to 12 days shorter than a
solar year. Some lunar calendars do not use intercalation, for example the
lunar Hijri calendar used by most Muslims. For those that do, such as the
Hebrew calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel ...
, and Buddhist Calendars in Myanmar, the most common form of intercalation is to add an additional month every second or third year. Some lunisolar calendars are also calibrated by annual natural events which are affected by lunar cycles as well as the solar cycle. An example of this is the lunar calendar of the
Banks Islands, which includes three months in which the edible
palolo worm
''Palola viridis'', (or ''Eunice viridis)'' commonly known as the palolo worm, Samoan palolo worm, balolo, wawo, or nyale, is a Polychaeta species from the waters of some of the Pacific islands, including Samoa, Tonga, Fiji, Vanuatu, and the isla ...
s mass on the beaches. These events occur at the last quarter of the lunar month, as the reproductive cycle of the palolos is synchronized with the moon.
Start of the lunar month
Lunar and lunisolar calendars differ as to which day is the first day of the month. In some lunisolar calendars, such as the
Chinese calendar, the first day of a month is the day when an astronomical
new moon occurs in a particular time zone. In others, such as some
Hindu calendar
The Hindu calendar, Panchanga () or Panjika is one of various lunisolar calendars that are traditionally used in the Indian subcontinent and Southeast Asia, with further regional variations for social and Hindu religious purposes. They adopt ...
s, each month begins on the day after the full moon. Others are based on the first sighting of the
lunar crescent, such as the
lunar Hijri calendar (and, historically, the
Hebrew calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel ...
).
Length of the lunar month
The length of each lunar cycle varies slightly from the average value. In addition, observations are subject to uncertainty and weather conditions. Thus to avoid uncertainty about the calendar, there have been attempts to create fixed arithmetical rules to determine the start of each calendar month.
The average length of the
synodic month is 29.53059 days.
Thus it is convenient if months generally alternate between 29 and 30 days (sometimes termed respectively "''hollow''" and "''full''"). The distribution of ''hollow'' and ''full'' months can be determined using
continued fractions, and examining successive approximations for the length of the month in terms of fractions of a day.
In the table below, the first column gives a sequence of such continued fractions. So to devise a calendar from each, one would take the number of days as given in the numerator and divide it into the number of months as given in the denominator. The second column shows, for reference, the time length of that cycle in years and days. The next double column shows how many of the months must be full and how many must be hollow; in each case, there is only one possible combination (how they are ordered within the cycle is not relevant).
The next column shows the decimal value of each fraction; that is the effective average length of a month over one cycle. It will be noted that each successive value comes closer to the length of the synodic month. Finally, the last two columns show roughly how long it will take (assuming one adheres to the pattern exactly) for the calendar months to be about a day off the synodic month, and which way off it will be.
These fractions can be used to construct a lunar calendar, or in combination with a solar calendar to produce a
lunisolar calendar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in ...
. A 49-month cycle was proposed as the basis of an alternative
Easter computation by
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, Theology, theologian, and author (described in his time as a "natural philosophy, natural philosopher"), widely ...
around 1700.
Reform of the Julian Calendar as Envisioned by Isaac Newton
by Ari Belenkiy and Eduardo Vila Echagüe (pdf); Notes and Records of the Royal Society of London (vol. 59, no. 3, pp. 223–254). The tabular Islamic calendar's 360-month cycle is equivalent to 24 of the cycles, minus a correction of one day. It comes to 10,631 days (29 years, including 7 leap years + 39 days) with 191 months of 30 days and 169 months of 29 days.
List of lunar calendars
* Gezer Calendar
* Haida Calendar
* Igbo calendar
* Islamic calendar
The Hijri calendar ( ar, ٱلتَّقْوِيم ٱلْهِجْرِيّ, translit=al-taqwīm al-hijrī), also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 ...
* Javanese calendar
The Javanese calendar ( jv, ꦥꦤꦁꦒꦭ꧀ꦭꦤ꧀ꦗꦮ, Pananggalan Jawa) is the calendar of the Javanese people. It is used concurrently with two other calendars, the Gregorian calendar and the Islamic calendar. The Gregorian calendar ...
* Maramataka (Māori lunar calendar)
* Yoruba calendar
The Yoruba calendar (''Kọ́jọ́dá'') is a calendar used by the Yoruba people of southwestern and north central Nigeria and southern Benin. The calendar has a year beginning on the last moon of May or first moon of June of the Gregorian cal ...
See also
* List of calendars
This is a list of calendars. Included are historical calendars as well as proposed ones. Historical calendars are often grouped into larger categories by cultural sphere or historical period; thus O'Neil (1976) distinguishes the groupings Egyptian ...
* Lunar phase
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the t ...
* Epact
* Paschal Full Moon
*Particular calendars
** Babylonian calendar
** Celtic calendar
** Chinese, Japanese, Korean, Vietnamese and Mongolian calendars
** Egyptian calendar
The ancient Egyptian calendar – a civil calendar – was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of five epagomenal days treated as outside of the year proper. Ea ...
** Ancient Greek calendars
** Hebrew calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel ...
** Hindu calendar
The Hindu calendar, Panchanga () or Panjika is one of various lunisolar calendars that are traditionally used in the Indian subcontinent and Southeast Asia, with further regional variations for social and Hindu religious purposes. They adopt ...
** Iranian calendars
The Iranian calendars or Iranian chronology ( fa, گاهشماری ایرانی, ) are a succession of calendars invented or used for over two millennia in Iran, also known as Persia. One of the longest chronological records in human history, ...
** Islamic calendar
The Hijri calendar ( ar, ٱلتَّقْوِيم ٱلْهِجْرِيّ, translit=al-taqwīm al-hijrī), also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 ...
** Ancient Macedonian calendar
** Mayan calendar
** Roman calendar
The Roman calendar was the calendar used by the Roman Kingdom and Roman Republic. The term often includes the Julian calendar established by the reforms of the dictator Julius Caesar and emperor Augustus in the late 1stcenturyBC and some ...
** Thai lunar calendar
** Tibetan calendar
The Tibetan calendar (), or Tibetan lunar calendar, is a lunisolar calendar, that is, the Tibetan 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 ...
Notes
References
External links
{{DEFAULTSORT:Lunar Calendar