The Indian national calendar, sometimes called the Shaka calendar or Śaka calendar, is a solar calendar that is used alongside the Gregorian calendar by The Gazette of India, in news broadcasts by All India Radio, and in calendars and official communications issued by the Government of India. Śaka Samvat is generally 78 years behind the Gregorian Calendar, except from January to March, when it is behind by 79 years.
Through historical Indian influence, the Śaka calendar is also used in Java and Bali among Indonesian Hindus. Nyepi, the "Day of Silence", is a celebration of the Śaka new year in Bali. Nepal's Nepal Sambat evolved from the Śaka calendar. The Śaka calendar was also used in several areas in the modern-day Philippines as written in the Laguna copperplate inscription. In India, Yugabda is also used with corresponding months of Śaka/Nepal Sambat. Yugabda is based on Kaliyuga Sankhya preserved by Indian Astrology. The Kali Yuga began years ago and has years left as of CE. Kali Yuga will end in the year 428,899 CE.
Calendar structure
The calendar months follow the signs of the tropical zodiac rather than the sidereal zodiac normally used with the Hindu and Buddhist calendars.
Caitra is the first month of the calendar and begins on the March equinox, similar to Farvardin, the first month of the Iranian Solar Hijri calendar. Chaitra has 30 days and starts on 22 March, except in leap years, when it has 31 days and starts on 21 March. The months in the first half of the year all have 31 days, to take into account the slower movement of the sun across the ecliptic at this time.
The names of the months are derived from the older Hindu lunisolar calendar, so variations in spellings exist, and there is a possible source of confusion as to what calendar a date belongs to.
The names of the weekdays are derived from the seven classical planets (see Navagraha). The first day of the week is Ravivāra (Sunday). The official calendar reckoned by the government of India has Sunday as the first and Saturday as the last day of the week.
Years are counted in the Shaka era, which starts its year 0 in the year 78 CE of the Common Era. To determine leap years, add 78 to the Shaka year – if the result is a leap year in the Gregorian calendar, then the Shaka year is a leap year as well.
History
Śaka Period
According to the Indian government sources, the Satavahana king Shalivahana is believed to have created the calendar that came to be known as the Śaka Calendar after he defeated Śaka rulers. But the origin of the Shaka era is highly controversial. According to scholars, the beginning of the Shaka era is widely equated to the ascension of Indo-Scythian king Chashtana in 78 CE.
Adoption
Senior Indian Astrophysicist Meghnad Saha was the head of the Calendar Reform Committee under the aegis of the Council of Scientific and Industrial Research. Other members of the committee were: A. C. Banerjee, K. L. Daftari, J. S. Karandikar, Gorakh Prasad, R. V. Vaidya and N. C. Lahiri. It was Saha's effort, which led to the formation of the committee. The task before the committee was to prepare an accurate calendar based on scientific study, which could be adopted uniformly throughout India. The committee had to undertake a detailed study of thirty different calendars prevalent in different parts of the country. The task was further complicated by the integration of those calendars with religion and local sentiments. India's first prime minister, Jawaharlal Nehru, in his preface to the Report of the committee, published in 1955, wrote: "They (different calendars) represent past political divisions in the country ... . Now that we have attained Independence, it is obviously desirable that there should be a certain uniformity in the calendar for our civic, social, and other purposes, and this should be done on a scientific approach to this problem." Usage started officially at 1 Chaitra 1879, Shaka Era, or 22 March 1957.