INTRODUCTION
Calendars are usually organised on the basis of cycles of the moon or sun. A calendar keeps an account of time in terms of days, months and years. It has great socio-economic and religious importance and makes life of people easier.
TYPES OF CALENDAR SYSTEMS
Solar Calendar
The solar calendar indicates seasonal changes observed due to apparent movement of the sun along with astronomical observations. The time period between two consecutive solstices or equinoxes (when the position of earth’s equator passes through the axis of sun) is taken as a year, which sums up to 365 days approximately.
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.The closest relationship between the year and the seasons is maintained by this arrangement. The solar year has a total of 12 months.
Tropical Solar Calendar: It takes into account the position of the sun with respect to Earth’s equator, that is, equinox.
Sidereal Solar Calendar: It takes into account position of stars, that is, astronomical observations around the sun.
Lunar Calendar
It is based on the apparent movement of the moon throughout the month. The lunar year is made up of 12 months, or lunations, just like the solar year. Each lunation, on the other hand, is a synodic month, as defined by the time between two successive full moons or new moons.
The length of a lunar month fluctuates from 29.26 to 29.80 days; it has a duration of 354 days, which is 11 days shorter than the solar year. This discrepancy is compensated for via intercalation which aligns the lunar and solar calendars.
Every 2.5 years, an intercalary month is added to the lunar calendar to align it with the solar calendar.
Adhik Masa is the name given to this extra month, often known as an intercalary month. This month is dedicated to God Vishnu and known as Purushottam Mass.
Luni-Solar Calendar
It indicates both the moon’s phases and position of the sun.
It is almost equivalent to solar calendar. Here the year is calculated by the solar cycle and the months by the lunar divisions as in the Hindu calendars, the adjustment between the two is brought about by intercalation and suppression of days and months. A Luni-Solar calendar generally consists 12 months but a 13th month is added as a leap month to realign months along seasons.
Hijri Calendar
This calendar has Arabic origin. Previously known as Amulfil, the term Hijri or hejira was coined after the death of Prophet Mohammed to commemorate his hijrah, or journey from Mecca to Madina, which occurred in 622 A.D. This year was designated as the Hijri era’s zero years.
This calendar has a lunar year that is divided into 12 months and has 354 days in a year. In this calendar, the day begins with a sunset.
The 12 months of the Hijri era are as follows:
Muharram – the first month, during which no business or travel is permitted.
Because the difference between the solar year and the lunar year is not adjusted under the Hijri calendar, the months are completely lunar and occur in such a sequence that there is no relation whatsoever to the cycle of the seasons of the solar year. As a result, it is one year behind the Gregorian calendar, which is based on the solar year, every 33 years.
Many Muslim countries use it to timestamp events at the same time as the Gregorian calendar.
This calendar is used by Muslims all across the world to determine the right days to observe Ramadan, perform Hajj, and celebrate other Islamic festivals.
Julian Calendar
It was proposed by Roman ruler Julius Caesar. It came into use in 45 BC. It is solar calendar. Greek astronomer Sosigenes of Alexandria played an important role in its development. In this, leap year comes after every 4 years. It replaced old moon calendar which was based on the cycle of moon.
Gregorian Calendar
It is the most widely used calendar in the world. In October 1582, the Gregorian calendar was implemented. It replaced Julian calendar. It was invented by Pope Gregory XIII.
The Earth’s cycle around the Sun is calculated using this calendar, which adds leap years to make the average year 365.2425 days long.
It is a solar year that begins on January 1st and lasts 365 days, 5 hours, 48 minutes, and 46 seconds.
Because these extra hours could not be included in the calendar for a year, the device of intercalation was used, and the system of adding one day to February every four years became popular.
CLASSIFICATION OF MONTHS
Solar Month
In the solar year, the months are 12 in number and bear the names of the twelve zodiac signs called Rashis or mansions by which they are also known in some parts of India. These twelve rashis are Mesha (Aries); Vrishabham (Taurus); Mithuna, the pairs (Gemini); Karka, the crab (Cancer); Simha, the lion (Leo); Kanya, the maiden (Virgo); Tula, the scales (Libra); Vrischika, the scorpion (Scorpio); Dhanus, the bow (Sagittarius); Makara, the sea monster (Capricorn); Kumbha, the water pot (Aquarius); Mina, the fish (Pisces).
Lunar Month
There are two methods for the commencement of the month under lunar system. They are either Amasanta or Purnimanta, i.e., they commence either with the bright fortnight (Bright-half) or with the dark fortnight (Dark-half) on the day following either the new moon or the full moon, respectively.The lunar month or the moon month which is followed in most parts of the nation.
Adhik Masa
Adhik Masa is an intercalary month added to a lunar year every 2.5 years to compensate for the difference between the lunar year and the solar year. It ensures that natural events and seasonal cycles that occurred in specific months were not disrupted by falling into different months. A lunar year is made up of 354 days and thus falls 11 days short of a solar year every year. To compensate for these 11 days, an intercalary month known as Adhik Masa or Mala Masa is
added to the Lunar Calendar every 2.5 years.
The months in the various calendar forms are divided into Pakshas or fortnights, weeks and days. The two Pakshas or fortnights under Lunar Calendar are:
Shukla Paksha (the bright half) which starts with the day following the new moon, and
Krishna Paksha (the dark half) which starts with the day following the full moon.
Tithi or Vasara refers to the lunar day, whereas Divasa refers to the solar day. The duration of a tithi, or lunar day, is shorter than that of a divasa, or solar day, which covers day and night from one sunrise to the next. Tithi has an average duration of 23 hours and 37 minutes, which is 23 minutes shorter than a divasa or solar day.
Ghatika, Pala, and Vipala are the sub-divisions of Tithi.
Indian Calendar Forms
In India, various forms of calendars came into picture based on the various eras to which it relates.
There are four types of calendars used in India.
• Vikram Samvat
• Saka Samvat
• Hijri calendar
• Gregorian calendar
Vikram Samvat
The Vikram era, which began in 57 BC, is widely used across India, with the exception of Bengal. It is believed to have been established by King Vikramaditya of Ujjain to commemorate his victory over the Saka rulers. However, some historians argue that the Vikram Samvat was originally initiated by the Malwa Ganarajya, known as the Malwa Gana era, and was later named after Chandragupta Vikramaditya following his conquest of Malwa around 400 AD. The Vikram Samvat is a luni-solar calendar rooted in ancient Hindu traditions.
The calendar is 56.7 years ahead of the Gregorian solar calendar. The new year begins the day after the new moon in the month of Chaitra, which typically falls in March or April on the Gregorian calendar. In Nepal, it starts in mid-April, marking the beginning of the solar new year. The Vikram Samvat year consists of 354 days, divided into 12 months: Chaitra, Vaisakha, Jyeshtha, Ashadha, Sravana, Bhadrapada, Ashwina, Kartika, Margashirsha, Pausha, Magha, and Phalguna.
Each month is divided into two fortnights: the bright half and the dark half. To account for the 11-day difference between the lunar and solar years, an additional month called Adhik Masa is added every three years. In some years, there are 13 months. The zero year of the Vikram Samvat is considered 57 BC.
Saka Samvat
The Saka calendar was established by King Shalivahan in 78 AD and is also referred to as the Saka era, named after the Saka tribe to which Shalivahan belonged. There is some historical debate about whether Shalivahan was a Saka himself or if he conquered the Sakas. Similar to the Vikram Samvat, the Saka calendar is a luni-solar system, incorporating lunar months and a solar year, with the same number of months as the Vikram calendar. However, the start dates for the months differ between the two systems.
The Saka calendar begins its zero year near the vernal equinox in 78 AD. The year starts on March 22nd each year, except in Gregorian leap years when it begins on March 21st. It follows a fixed number of days for each month. The months in the Saka calendar are the same as in the Vikram Samvat: Chaitra, Vaisakha, Jyeshtha, Ashadha, Shravana, Bhadrapada, Ashwina, Kartika, Margashirsha, Pausha, Magha, and Phalguna, with a total of 365 days in a year.
In Indonesia, the Saka New Year, known as Nyepi or the ‘Day of Silence,’ is celebrated in Bali and Java. In 1957, the Saka calendar was officially adopted by the Indian government as the national calendar of India.
IMPORTANT ASTRONOMICAL CONCEPTS & IDEAS
Pachanga
The Vedas contain reference of Panchanga. It takes into account panch, i.e., five angas or limbs, viz., year, month, paksha, tithi and ghatika or alternatively, tithi, vaara, nakshatra, yoga and karana. In eastern states like Odisha, Assam and Bengal, Panchanga is known as Panjika.
Nakshatra
The twelve places or rashis through which the Sun passes during a year are named after group of stars called Nakshatras. There are 28 nakshatras or constellations in total. Nakshatras, being unequal in size, do not have the same number of stars, some have even one or two. Each rashi consists of two to three nakshatras.
Uttar Ayana: It indicates northwards movement of earth in relation to the sun on the celestial sphere. First six months from Makara Sankranti to Karka Sankranti, i.e. from Paush (January) to Ashadh (June). It constitutes single day for the Gods.
Uttarayan and Dakshinayan
Dakshiyana: It is the period between summer solstice and winter solstice. It marks southwards journey or movement of the earth on the day od summer solstice. It is period between Karka Sankranti and Makara Sankranti. It represents single night of the Gods.
The Four Eras or Yugas
According to Hindu beliefs, Yuga refers to an epoch or era with a four age-cycle. The four age cycles or Yugas in
ascending order are:
• Satya Yuga or Krta Yuga equals 1,728,000 years
• Treta Yuga equals 1,296,000 years
• Dvapara Yuga equals 864,000 years
• Kali Yuga equals 432,000 years
These four Yugas constitute one Mahayuga and equals 4.32 million human years. There are 1,000 Mahayugas in one day
of Brahma or 4.32 billion human years. A Mahakalpa consists of 100 years of Brahma.
Krta Yuga (Satya Yuga): This is the first and the golden age, known for truth and perfection. During this Yuga, there was one religion, and all people were virtuous. No religious rituals were necessary as everyone could achieve supreme bliss. The earth provided all resources naturally, and there was no need for agriculture or mining. The climate was always favorable, and people lived in harmony, free from disease and fear.
Treta Yuga: In this second age, virtue began to decline. Numerous emperors emerged, expanding their empires through frequent wars. The climate became more extreme, and oceans and deserts formed. Agriculture, labor, and
mining were introduced. The average lifespan of humans decreased, ranging from 1,000 to 10,000 years.
Dvapara Yuga: During this age, human beings became tainted by tamasic qualities and were no longer as strong as their ancestors. Diseases spread widely, and people became dissatisfied and often fought among themselves. Human lifespan shortened further, with most people living only a few centuries.
Kali Yuga: The final and darkest age, characterized by ignorance and moral decay. People became sinful and devoid of virtue, enslaved by their desires. Their strength was minimal compared to those in the earlier Yugas. The average lifespan dropped to around 100 years, and by the end of this age, it is believed to decline further to just 20 years.
