Hindu calendar

The Vedic culture developed a sophisticated time keeping methodology and calendars for Vedic rituals, and timekeeping as well as the nature of solar and Moon movements are mentioned in Vedic texts. For example, Kaushitaki Brahmana chapter 19.3 mentions the shift in the relative location of the Sun towards north for 6 months, and south for 6 months. Time keeping was important to Vedic rituals, and Jyotisha was the Vedic era field of tracking and predicting the movements of astronomical bodies in order to keep time, in order to fix the day and time of these rituals. This study is one of the six ancient Vedangas, or ancillary science connected with the Vedas. Yukio Ohashi states that this Vedanga field developed from actual astronomical studies in the ancient Vedic Period. The texts of Vedic Jyotisha sciences were translated into the Chinese language in the 2nd and 3rd centuries CE, and the Rigvedic passages on astronomy are found in the works of Zhu Jiangyan and Zhi Qian. According to Subhash Kak, the beginning of the Hindu calendar was much earlier. He cites Greek historians describing Maurya kings referring to a calendar which originated in 6676 BCE known as Saptarsi calendar. The Vikrami calendar is named after king Vikramaditya and starts in 57 BCE. ==Texts==

Hindu scholars kept precise time by observing and calculating the cycles of Surya (the Sun), Moon and the planets. These calculations about the Sun appear in various astronomical texts in Sanskrit, such as the 5th-century Aryabhatiya by Aryabhata, the 6th-century Romaka by Latadeva and Panca Siddhantika by Varahamihira, the 7th-century Khandakhadyaka by Brahmagupta and the 8th-century Sisyadhivrddida by Lalla. These texts present Surya and various planets and estimate the characteristics of the respective planetary motion. For example, the 1st millennium CE Hindu scholars calculated the sidereal length of a year as follows, from their astronomical studies, with slightly different results: The Hindu texts used the lunar cycle for setting months and days, but the solar cycle to set the complete year. This system is similar to the Jewish and Babylonian ancient calendars, creating the same challenge of accounting for the mismatch between the nearly 354 lunar days in twelve months, versus over 365 solar days in a year. Like other ancient human cultures, Hindus innovated a number of systems of which intercalary months became most used, that is adding another month every 32.5 months on average. == Astronomical basis ==

The Hindu calendar is based on a geocentric model of the Solar System. A large part of this calendar is defined based on the movement of the Sun and the Moon around the Earth (saura māna and cāndra māna respectively). Furthermore, it includes synodic, sidereal, and tropical elements. Many variants of the Hindu calendar have been created by including and excluding these elements (solar, lunar, lunisolar etc.) and are in use in different parts of India. ==Year: Samvat==

Samvat refers to era of the several Hindu calendar systems in Nepal and India, in a similar manner to the Christian era. There are several samvat found in historic Buddhist, Hindu and Jain texts and epigraphy, of which three are most significant: Vikrama era, Old Shaka era and Shaka era of 78 CE. • Vikram Samvat (Bikram Sambat): A northern Indian almanac which started in 57 BCE, and is also called the Vikrama Era. It is related to the Bikrami calendar, and is apocryphally linked to Vikramaditya. The year starts from the month of Baishakh / Vaishakha. This system is common in epigraphic evidence from northern, western, central and eastern Indian subcontinent, particularly after the early centuries of the 1st millennium CE. • Saka era of Southeast Asia: The Hindu calendar system in Indonesia is attributed to the legend of Hindus arriving with a sage Aji Saka in 1st-century Java, in March 78 CE. Numerous ancient and medieval era texts and inscriptions found in Indonesian islands use this reference year. • Indian national calendar (modern): combines many Hindu calendars into one official standardized one, but old ones remain in use. ==Months==

Solar months and seasons The Hindu calendar divides the zodiac into twelve divisions called rāśhi ("group, amount, collection"; Hindi: ). The Sun appears to move around the Earth through different divisions/constellations in the sky throughout the year, which in reality is actually caused by the Earth revolving around the Sun. The rāśis have 30° each and are named for constellations found in the zodiac. The time taken by the Sun to transit through a rāśi is a solar month whose name is identical to the name of the rāśi. In practice, solar months are mostly referred as rāśi (not months). The solar months are named differently in different regional calendars. While the Malayalam calendar broadly retains the phonetic Sanskrit names, the Bengali and Tamil calendars repurpose the Sanskrit lunar month names (Chaitra, Vaishaka etc.) as follows: • The Tamil calendar replaces Mesha, Vrisha etc. with Chithirai, Vaigasi etc. • The Bengali calendar is similar to the Tamil calendar except in that it starts the year with Boiśākh (instead of Choitrô), followed by Jyoisthô etc. The Assamese and Odia calendars too are structured the same way. The solar months (rāśi) along with their equivalent names in the Bangali, Malayalam and Tamil calendar are given below: The solar months (rāśi) along with the approximate correspondence to Hindu seasons (Ṛtu) and Gregorian months are: The other half is the darkening, waning fortnight which ends in the new moon. This is called "Vadhya Paksha" or Krishna Paksha. Amānta and Purnimānta systems Two traditions have been followed in the Indian subcontinent with respect to lunar months: the amānta tradition, which ends the lunar month on the new moon day and the purnimānta tradition, which ends on the full moon day. As a consequence, in the amanta tradition, Shukla paksha precedes Krishna paksha in every lunar month, whereas in the purnimānta tradition, Krishna paksha precedes Shukla paksha in every lunar month. Hence, Shukla paksha will always belong to the same month in both traditions, whereas Krishna paksha will always be associated with different but succeeding months in each tradition. The amanta (also known as Amāvasyānta or Mukhyamana) tradition is followed by most Indian states that have a peninsular coastline (except Assam, West Bengal, Odisha, Tamil Nadu and Kerala, which use their own solar calendars). These states are Gujarat, Maharashtra, Goa, Karnataka, Andhra Pradesh and Telangana. Nepal and most Indian states north of the Vindhya mountains follow the poornimānta (or Gaunamana) tradition. The poornimānta tradition was being followed in the Vedic era. It was replaced with the amanta tradition as the Hindu calendar system prior to the 1st century BCE, but the Poornimanta tradition was restored in 57 BCE by king Vikramaditya, who wanted to return to the Vedic roots. The two traditions of Amanta and Purnimanta systems have led to alternate ways of dating any festival or event that occurs in a Krishna paksha in the historic Hindu, Buddhist or Jain literature, and contemporary regional literature or festival calendars. For example, the Hindu festival of Maha Shivaratri falls on the fourteenth lunar day of ''Magha's Krishna paksha in the Amanta system, while the same exact day is expressed as the fourteenth lunar day of Phalguna's'' Krishna paksha in the Purnimanta system. Both lunisolar calendar systems are equivalent ways of referring to the same date, and they continue to be in use in different regions, though the Purnimanta system is now typically assumed as implied in modern Indology literature if not otherwise specified. The Hindu mathematicians who calculated the best way to adjust the two years, over long periods of a yuga (era, tables calculating 1000s of years), they determined that the best means to intercalate the months is to time the intercalary months on a 19-year cycle, similar to the Metonic cycle used in the Hebrew calendar. This intercalation is generally adopted in the 3rd, 5th, 8th, 11th, 14th, 16th and 19th year of this cycle. Further, the complex rules rule out the repetition of Mārgaśīrṣa (also called Agrahayana), Pausha and Magha lunar months. The historic Hindu texts are not consistent on these rules, with competing ideas flourishing in the Hindu culture. Rare corrections The Hindu calendar makes further rare adjustments, over a cycle of centuries, where a certain month is considered kshaya month (dropped). This occurs because of the complexity of the relative lunar, solar and earth movements. Underhill (1991) describes this part of Hindu calendar theory: "when the sun is in perigee, and a lunar month being at its longest, if the new moon immediately precedes a sankranti, then the first of the two lunar months is deleted (called nija or kshaya)." This, for example, happened in the year 1 BCE, when there was no new moon between Makara sankranti and Kumbha sankranti, and the month of Pausha was dropped. ==Day==

Just like months, the Hindu calendar has two measures of a day, one based on the lunar movement and the other on solar. The solar (saura) day or civil day, called divasa (), has been what most Hindus traditionally use, is easy and empirical to observe, with or without a clock, and it is defined as the period from one sunrise to another. The lunar day is called tithi (), and this is based on complicated measures of lunar movement. A lunar day or tithi may, for example, begin in the middle of an afternoon and end next afternoon. Both these days do not directly correspond to a mathematical measure for a day such as equal 24 hours of a solar year, a fact that the Hindu calendar scholars knew, but the system of divasa was convenient for the general population. The tithi have been the basis for timing rituals and festivals, while divasa for everyday use. The Hindu calendars adjust the mismatch in divasa and tithi, using a methodology similar to the solar and lunar months. A tithi is technically defined in Vedic texts, states John E. Cort, as "the time required by the combined motions of the Sun and Moon to increase (in a bright fortnight) or decrease (in a dark fortnight) their relative distance by twelve degrees of the zodiac. These motions are measured using a fixed map of celestial zodiac as reference, and given the elliptical orbits, a duration of a tithi varies between 21.5 and 26 hours, states Cort. Weekday/Vāsara Vāsara refers to the weekdays in Sanskrit. Also referred to as Vara and used as a suffix. The correspondence between the names of the week in Hindu and other Indo-European calendars are exact. This alignment of names probably took place sometime during the 3rd century CE. • Vava or Bava (बव) • Valava or Bālava (बालव) • Kaulava (कौलव) • Taitila or Taitula (तैतिल) • Gara or Garaja (गरज) • Vaṇija (वणिज) • Viṣṭi (Bhadra) (भद्रा) • Now the first half of the 1st tithi (of Śukla Pakṣa) is always Kiṃtughna karaṇa. Hence this karaṇa is "fixed". • Next, the 7-repeating karaṇas repeat eight times to cover the next 56 half-tithis. Thus these are the "repeating" (cara) karaṇas. • The 3 remaining half-tithis take the remaining "fixed" karaṇas in order. Thus these are also "fixed" (sthira). • Thus one gets 60 karaṇas from those 11 preset karaṇas. The Vedic day begins at sunrise. The karaṇa at sunrise of a particular day shall be the prevailing karaṇa for the whole day. Nakshatra Nakshatras are divisions of ecliptic, each 13° 20', starting from 0° Aries. ==Festival calendar: Solar and Lunar dates==

Many holidays in the Hindu, Buddhist and Jaina traditions are based on the lunar cycles in the lunisolar timekeeping with foundations in the Hindu calendar system. A few holidays, however, are based on the solar cycle, such as the Vaisakhi, Pongal and those associated with Sankranti. The dates of the lunar cycle based festivals vary significantly on the Gregorian calendar and at times by several weeks. The solar cycle based ancient Hindu festivals almost always fall on the same Gregorian date every year and if they vary in an exceptional year, it is by one day. ==Regional variants==

The Hindu Calendar Reform Committee, appointed in 1952, identified more than thirty well-developed calendars, in use across different parts of India. Variants include the lunar emphasizing Vikrama, and the Shalivahana calendars, as well as the solar emphasizing Tamil calendar and Malayalam calendar. The two calendars most widely used today are the Vikrama calendar, which is in followed in western and northern India and Nepal, the Shalivahana Shaka calendar which is followed in the Deccan region of India (Comprising present day Indian states of Telangana, Andhra Pradesh, Karnataka, Maharashtra, and Goa). Lunisolar Calendars based on lunar cycle (lunar months in solar year, lunar phase for religious dates and new year): • Vikram Samvat (lunisolar) • Vikrami era – North and Central India (Lunar) • Gujarati samvat – Gujarat, Rajasthan • Sindhi calendar – Sindhis • Shalivahana (Shaka) calendar – Used in Deccan region states of Maharashtra, Goa, Karnataka, Andhra Pradesh, Telangana • Telugu Calendar - Andhra Pradesh and Telangana • Kannada Calendar - Karnataka • Marathi Calendar - Maharastra • Saptarishi calendar – Kashmiri Pandits • Meitei calendar – Manipur • Nepali calendar – Nepal, Sikkim (Newar) • Punjabi calendar – Punjab • Tibetan calendar – Tibet, Ladakh, Himachal Pradesh (Spiti), Sikkim, Arunachal Pradesh (Monpa) Solar Calendars based on solar cycle (solar months in solar year, lunar phase for religious dates but new year which falls on solar date – South and Southeast Asian solar New Year): • Assamese calendar – Assam • Bengali calendar – West Bengal, Bangladesh, Assam (Barak Valley), Tripura • Odia calendar – Odisha • Tirhuta calendar – Bihar (Maithils) • Tripuri calendar – Tripura • Malayalam calendar – Kerala • Tamil calendar – Tamil Nadu • Tulu calendar – Karnataka (Tulus) • Vikram Samvat (solar) – Nepal, Sikkim • Theravada Buddhist calendar – Arunachal Pradesh (Khamti, Singpho, other Tais) • Burmese calendar – Tripura (Mog) Other related calendars across India and Asia • Indian national calendar – used by Indian Government (civil calendar based on solar months) • Vira Nirvana Samvat (Lunar) – Jain • Pawukon calendar – Bali • Balinese saka calendar (Lunar) – Bali • Cham calendar (Lunar) – Chams • Chula Sakarat (Lunar) – Myanmar • Thai solar calendar – Thailand • Thai lunar calendar – Thailand • Khmer calendar (Lunar & Solar) – Cambodia ==See also==