Tamil calendar

There are several references to the calendar in early Tamil literature. Nakkeerar, the Sangam period author of the Neṭunalvāṭai, wrote in the third century CE that the Sun travels each year from Mesha/Chittirai in mid-April through 11 successive signs of the zodiac.^[4] The same is referenced to by Kūdalūr Kiḻar in Puṟanāṉūṟu.^[5][6] Tolkappiyam, the oldest surviving Tamil grammar text, divides the year into six seasons and Chittirai marks the start of the "ilavenil" (summer) season.^[7] The fifth century CE treatise of Cilappatikaram mentions the 12 rāśis (zodiac signs) that correspond to the Tamil months.^[8] The sixth century epic Manimekalai alludes to this to the Hindu solar calendar.^[9]

Inscriptional evidences from Pagan in Myanmar from the 11th century CE and in Sukhothai in Thailand from the 14th century CE point to South Indian courtiers being tasked with defining the traditional calendar that followed a similar cycle.^[10][11]

The Tamil calendar is based on the Hindu system of calendrics that was used to calculate date and time.^[12] The Tirukkanida Panchanga derived from astronomical data is used as a basis for the same.^[13] The calendar is similar to traditional calendars followed in other parts of the Indian subcontinent, and Southeast Asia.^[14]

The Tamil calendar follows a 60-year cycle similar to the other traditional calendars of India.^[15] The Tamil New Year follows the Nirayana system, and usually falls on 13 or 14 April in the Gregorian year.^[16] The new year starts on the date arrived by adding the days corresponding to the 23 degrees of trepidation (oscillation) to the vernal equinox, when the Sun begins its transition as per the Hindu sidereal calendar.^{[17][page needed]} A Tamil calendar year might consist of 365 or 366 days in a year.^[18]

The 60-year cycle is common to Hindu traditional calendars, with similar names and sequence of years. The earliest reference of the same is in Surya Siddhanta, dated between 4th and 9th century CE. There are parallels to the sexagenary cycle used in the Chinese calendar,^[19][20][21] though which influenced the other has been subject to debate.^[22]

After the completion of a cycle of sixty years, the calendar re-starts with the first year of a new cycle.^[23] As per the Hindu Panchangam, it represents the year in which Shani Saturn (which takes 30 years to complete one cycle round the Sun) and Vyalan (Jupiter) (which takes 12 years to complete one cycle round the Sun) come to a same position after 60 years.^[24][25]

The following list presents the current 60-year cycle of the Tamil calendar:^[26]

There are twelve months in the Tamil calendar, with 29 to 32 days per month.^[27] Tamil months start and end based on the Sun's shift from one rasi to the other, and the names of the months are based on the nakshatra (star) that coincides with the start of the pournami (full moon) in that month.^[28] The Tamil calendar month starts a few days after the corresponding Hindu calendar month as the Tamil calendar is a solar calendar, while the other is a lunisolar calendar.^[29]

A Tamil year is divided into six seasons, each of which lasts two months.^[30][31]

The days of week (Kiḻamai) in the Tamil calendar relate to the celestial bodies in the Solar System: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn, in that order. A week usually starts with Sunday, and ends in a Saturday.^[32][33]

The various days and months of the Tamil Calendar are of specific significance to Tamil Hindus. The Vakiya Panchangam is employed for calculation of sacred days, while the Tirugaṇita Panchangam is employed for astrological calculations.^[34]

The months and their significant events and festivals are listed below.^[29][35]

• Chandravakyas
• Malayalam calendar
• Pambu Panchangam