A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically day, week, month, and year. A date is the designation of a single, specific day within such a system. A calender is also a physical record (often paper) of such a system.
Synchronisation of calendars is based on following three systems:
- Lunar calendars are synchronized to the motion of the Moon (lunar phases); an example is the Islamic calendar.
- The lunar year, like the solar year, consists of 12 months or lunations.
- Since a lunar month varies from 29.26 to 29.80 days, it gives a period of 354 days, necessarily short of 11 days to the solar year.
- This difference is accounted for by an intercalation or suppression, to make the lunar year confirm to the solar year. An intercalary month is introduced every 2 years and 6 months in the lunar year to adjust it to the solar year. This extra month or intercalary month is called Adhik Masa.
- Solar calendars are based on perceived seasonal changes synchronized to the apparent motion of the Sun; an example is the Persian calendar.
- The solar year consists of 365 days, 5 hours, 48 minutes and 46 seconds. This system maintains the closest correspondence between the year and the seasons. The solar year has 12 months in total.
- Luni-Solar calendars are based on a combination of both solar and lunar reckonings; examples include the traditional calendar of China, the Hindu calendar in India, and the Hebrew calendar.
Classification of Indian Calendar Forms
In India, four types of calendars are followed:
- Vikram Samvat (Hindu lunar calendar)
- Saka Samvat (Hindu Solar calendar)
- Hijri Calendar (Islamic lunar calendar)
- Gregorian Calendar (Scientific solar calendar)- followed universally
- The Vikram era started 57 years before the Christian era, i.e. around 57 BC and is in force in almost all of India except the region of Bengal.
- 57 B.C. is the zero year.
- This era as historians believe, is said to have been established by King Vikramaditya of Ujjain to commemorate his victory over the Saka rulers.
- It is a lunar calendar as it is based on the movement of the moon.
- It has 354 days in a year and every year is divided into 12 months namely Chaitra, Vaisakha, Jyeshtha, Ashadha, Sravana, Bhadrapada, Ashwina, Kartika, Margashirsha, Pausha, Magha and Phalguna and each month is divided into two phases.
- The bright half is called the Shuklapaksha (15 days). It starts with the new moon and ends with a full moon.
- The dark half is called the Krishnapaksha (15 days). It starts with the full moon and ends with a new moon.
- It was initiated by King Shalivahan.
- The zero year of Saka Samvat is 78 A.D.
- It is both solar and lunar calendar, with lunar months and solar year.
- It was adopted by the Government of India as the official calendar in the year 1957.
- Saka Calendar begins on 22nd March every year except in gregorian leap years when it starts on 21st March.
- Every year has 365 days.
- The names of the months in Saka Calendar are:
- Chhaitra (March 21 – April 20)
- Vaishakha (April 21-May 21)
- Jyeshtha (May 22-June 21)
- Ashadha (June 22- July 22)
- Shravana (July 23-August 22)
- Bhaadra (August 22-September 22)
- Ashwin (September 23-October 22)
- Kartika (October 23-November 21)
- Agrahayana (November 22-December 21)
- Pausha (December 22-January 20)
- Magha (January 21- February 19) and
- Phalguna (February 20-March 20/21)
- It is a lunar calendar.
- The zero year is 622 A.D.
- It was initially started and followed in Saudi Arabia.
- Every year has 12 months and 354 days.
- The first month is called Muharram (1st Muharram – Islamic New Year).
- Ninth month is called Ramzaan. During this month, people observe a fast for the purification of souls. The morning breakfast is called Shehri and evening food is called Iftar.
- The 12 months of the calendar are:
- Muharram – first month, during which any business or
travel is prohibited.)
- Safar – good for travel, business and fighting.
- Rabi’ al-awwal (Rabi’ I) – commencement of the spring.
- Rabi’ al-thani (Rabi’ II) – indicates end of the spring.
- Jumada al-awwal (Jumada I) – commencement of the cold season.
- Jumada al-thani (Jumada II) – conclusion of the cold season.
- Rajah – to make preparation to fence the fields.
- Sha’ban – the month of harvesting.
- Ramadan – ninth month with excessive heat when people keep fasts for purification of soul.
- Shawwal – a month to go out for hunting. (1st Shawwal – Eid-ul-Fitar)
- Dhu al-Qi’dah – month to get the camels ready for travel.
- Dhu al-Hijjah – last month, dedicated to pilgrimage. (8-13 Dhu-al-Hijjah: Hajj to Mecca)
- Muharram – first month, during which any business or
- Out of these 12 months, four months are considered sacred: 1st, 7th,
11th and 12th.
- The months are completely lunar and occur in such a sequence that there is no relation whatsoever either to the cycle of the seasons or the solar year, as the difference between the solar year and the lunar year is not adjusted under hijri calendar. Thus, it falls short of one year every 33 years compared to the Gregorian calendar which is based on solar year.
- This calendar is based on the birthday of the founder of Christianity, Jesus Christ.
- It is a solar year commencing from the first day of January and consists of 365 days, 5 hours, 48 minutes and 46 seconds.
- Since these extra hours could not be included in the calendar for a year, the device of intercalation was adopted and the system of adding one day every four years to the month of February came into vogue. The year under this calendar form is known as a civil year.
The Zoroastrian Calendar era commenced from 632 AD. Parsis in India use Shahenshahi Calendar, unlike Iranians who use Qadimi Calender. Under Shahenshahi Calender, Nowruz or new year usually occurs on March 20/21/22. Nowruz is day of vernal equinox.
National Calendar of India
- The Saka Calendar used as the official civil calendar in the country is the National Calendar of India. It is used, through notification in the Official Gazette by the Government of India, in news broadcasts by All India Radio, calendars and communication documents issued under the control of Government of India.
- The Saka calendar which is one of the Hindu calendar was originally named as Saka Samvat. It is also used for the calculation of days of religious significance in the Hindu Religion.
- The Saka calendar was adopted as the National Calendar in the year 1957 by the Calendar Reforms Committee set up by the Government of India. The Committee made efforts to co-incide the astronomical data and harmonise the usage of this calendar after rectification of some local errors.
- It came into use from 22 March 1957 according to the Gregorian calendar which was actually Chaitra 1, 1879 according to the Saka Samvat.
- It was adopted as the National Calendar of India in order to synchronise the usage of 30 different kinds of calendars used in India at that time.