Hindu calendar

Hindu calendar, dating system used in India from about 1000 bce and still used to establish dates of the Hindu religious year. It is based on a year of 12 lunar months; i.e., 12 full cycles of phases of the Moon. The discrepancy between the lunar year of about 354 days and the solar year of about 365 days is partially resolved by intercalation (adding extra months or days). Modern India has adopted the Gregorian calendar for its secular life, but Hindu religious life—from solemn rituals to boisterous festivals—continues to be arranged according to the traditional Hindu calendar.

A Hindu calendar is also called a panchangam, meaning “five limbs” (it is sometimes spelled panchanga or panchang). The five limbs are: lunar day (tithi), half-day (karana), constellation (nakshatra), angles of Sun and Moon (yoga), and solar weekday (vara). The full panchangam system has many technical details and regional variations, along with various overlapping systems of reckoning time. The Hindu calendar system also coincides with a ritually and socially significant system of astronomy and astrology (jyotisha) involving days of the week, planets, constellations, and times of day.

History and development

The Hindu calendar system has roots leading back to the Vedic era. (For a technical discussion of the history of the Hindu calendar system,see calendar: the Hindu calendar.) The early system posited a solar year of 360 days, with 12 months based on the phases of the Moon and 27 or 28 days per month based on the cycling of the Moon. Discrepancies with the solar year were solved with periodic intercalations of leap days or months.

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Vedic texts also mention the nakshatras, a list of 27 Indian constellations on the ecliptic through which the Moon rises successively in the course of its phases. The 27 nakshatras each equal roughly a day in length.

While time was reckoned according to the 27 nakshatras in early Vedic sources, it was simultaneously understood that a month theoretically had 30 lunar days (tithis) based on the phases of the Moon but that these days varied in the number of hours that they lasted, between 21.5 and 26 hours. These lunar days are the essential components of the panchangam system.

The year was further divided into six seasons that consisted of two months each. One set of names for those 12 months was used in Vedic sources. The list of months had been altered by the 4th century ce to form the current list of Hindu calendar months.

Through interactions with Hellenistic culture in the last centuries bce and first centuries ce, Indians encountered Greek and Mesopotamian notions for keeping track of time and adopted components into the Hindu calendar system. New additions included the seven-day week based on seven celestial bodies and a system of twelve zodiac signs. Both concepts were integrated into the Indian astrological system of nakshatras as well as Hindu mythology.

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Seasons, months, and days of the week

The six seasons of the Hindu year are meaningful for the ritual calendar, even if India’s climate has many regional variations where the weather does not precisely match the season’s described conditions. The intricate Sanskrit poem Ritusamhara (“Garland of the Seasons”)—attributed to the celebrated poet and playwright Kalidasa (c. 5th century ce)—consists of six cantos, one for each of the seasons. The poem interweaves naturalistic descriptions of the seasons with romantic imagery suggesting the rasa (Sanskrit poetic flavor) of romance and love (shringara).

Each season consists of two months, and each month is divided into two halves, or fortnights, called pakshas (“wings”), based on the waxing and waning of the Moon. The waning moon fortnight is called the krishna (“dark”) paksha, and the waxing moon fortnight is called the shukla (“bright”) paksha. Each half of the month contains 15 lunar days (tithis). Some observant Hindus fast on the 11th day (ekadashi) of each fortnight. The new moon (amavasya) and full moon (purnimasa) days also have special rituals observed by some adherents.

Different regions of India follow different ways of determining the beginning and end of these 12 months. Regions following the amavasyanta (or amanta) calendar conclude each month on the new moon day. Regions that follow the purnimanta calendar end the month on the full moon day. The purnimanta calendar is followed mostly in northern and northwestern Indian states and territories, while the amavasyanta calender is followed primarily in southern and eastern Indian states. Hindus in Nepal also follow the purnimanta calendar.

While traditional calendars count the 15 lunar days (tithis) of the two fortnights, the seven-day week is also followed. The names of the days of the seven-day week (saptaha) are based on celestial bodies: the Sun, Moon, and the first five planets of the solar system (excluding Earth). The name of each day in Sanskrit is comprised of the planet followed by the word for “day of the week”: vasara or vara. These same seven celestial bodies comprise the first seven navagrahas (“nine planets”)—the other two are “shadow” planets that are thought to cause eclipses and are associated with lunar nodes—which in turn are considered to be deities that control their respective days of the week. The exact words for each day of the week vary across different Indian languages and other countries of South and Southeast Asia, but the associations with the celestial bodies are largely the same.

Hindu astrology

The primary system of Hindu astronomy and astrology (jyotisha) is based on the system of nakshatras, or constellations, which have been in use since the Vedic period. The 27 nakshatras are lunar mansions through which the Moon passes along the ecliptic, each measuring an arc of 13° 20′ of the ecliptic. Each of the 27 nakshatras corresponds to approximately one day of a 27-day lunar month. The system is a form of sidereal time—time measured as the motion of Earth against the fixed stars. The location of the Moon in this cycle of nakshatras at the time of one’s birth is considered to be one’s nakshatra, and that sign is thought to be determinative of a person’s personality, career, relationships, and more. Certain nakshatras are thought to be more or less compatible for marriage, thus matching nakshatras often plays a role in Hindu marriage arrangements. For archana offerings—a specific form of puja in Hindu temples—the officiating priest (pujari) performing the ritual on a devotee’s behalf asks the devotee for their name, gotra (lineage), and nakshatra, which are then included in the priest’s recitations during the archana ritual. Internet sites that can calculate one’s nakshatra are readily available online.

The introduction of Mesopotamian and Greek concepts of astronomy and astrology into India also brought the solar-based zodiac signs, which Indians then used in conjunction with the nakshatras for astrological and prognostication purposes. The monthly entry of the Sun into a new zodiac sign (sankranti) also became significant for determining certain Hindu festivals. The names of the zodiac signs were taken from Western sources and translated into Sanskrit as the twelve rashis.

Within a given day, there are 30 muhurtas (also spelled muhurtam or muhurat), a period of approximately 48 minutes in Western reckoning. The locations of the planets and nakshatras during individual muhurtas are thought to make those times favorable or unfavorable for certain activities. A Hindu astrological expert can be contracted to draw detailed charts for births, marriages, and more. They are also consulted to find the best and most favorable muhurtas—as well as the unfavorable times—for activities such as solemnizing a marriage, performing a puja, starting a business, moving houses, or beginning a journey. The panchangam five-limb system and the muhurtas are based on the relative celestial positions of multiple entities, astrological reckonings are localized—a muhurta or nakshatra will be different depending on whether the ceremony or birth takes place in Chicago or New Delhi. Throughout India printed local calendars, specific to regional variations, languages, and India’s time zone, are readily available in shops. In diasporic settings outside India, many Hindus rely on online calculators that provide relevant astrological information.

Hindu festival calendar

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The dates of most major Hindu festivals (utsavas) are determined according to the Hindu months of the year, and thus they shift annually against the Gregorian solar calendar. A few holidays do follow the solar calendar and are based on the signs of the zodiac. For example Makar Sankranti, celebrated across India, marks the entrance of the Sun into the sign of Capricorn, as does the Tamil holiday Pongal. A few regions in India base their New Year observances on the entrance of the Sun into the sign of Aries—an occurrence called Mesha Sankranti—such as Vishu in Kerala, Puthandu in Tamil Nadu, Pohela Boisakh in Bengal, Bihu in Assam, and Vaisakhi in Punjab. Otherwise, the dates of most Hindu festivals are determined according to the lunar calendar of months.