Trying to make sense of the various “New Year” celebrations and calendars in India is quite a fun task.
India has two different kinds of calendars, broadly described as “lunisolar” (चान्द्रमान) and “solar” (सौरमान). Evidence from the Vedas indicates that a lunisolar calendar of the full-moon (पूर्णिमान्त) variety (which we shall see in a later section) was followed in those times. Today, we see a variety of calendars and variants followed in various states
As we can see, there are two major divisions of calendars into lunisolar and solar, plus variants of each kind.
To understand some of these differences, let's try to analyze the Indian Lunisolar calendar bottom-up.
Starting from zero
Calendars require definitions of days, months, and years.
The first thing you need for a calendar, is some sort of measure for a day. That's fairly easy to do, since the sun rises and sets once a day. Modern reckoning starts a day from midnight, but Indian calculations count a day from sunrise till the next sunrise.
Months
Next, we need a way to define a “month”. Looking up at the night sky, we can't fail to notice the changing phases of the moon, which gives us a convenient month measure.
A lunar month can be counted from new moon to new moon, or from full moon to full moon. Various Indian calendars do both. The new-moon (अमान्त) calendars, as the name would suggest, end a month on a new-moon day, and start the next month on the day following a new moon. Full-moon (पूर्णिमान्त) calendars, which are the older variants, start a month from the day following a full moon and end it at the next full moon. A glance at the graphic earlier in this post will reveal that southern and western states of India tend to follow the new-moon (अमान्त) system, while the northern states follow the full-moon (पूर्णिमान्त) system.
The period between two full (or new) moons, called the sun-synodic period of the moon, is 29.53 days on an average. Since the earth orbits the sun in an elipse, with slightly varying angular velocity (faster near perihelion), and the moon follows a similar pattern in its orbit around the earth, the sun-synodic period of the moon can vary between 29.18 to 29.93 days. Ancient astronomers in Greece and India had very good ways of calculating the apparent orbit of the moon, and could predict the phases of the moon reasonably accurately, making it a convenient month marker that could be calculated in advance.
Years
The cyclic rhythm of the seasons gives us a way to define years. There are six seasons (ऋतुः sing., ऋतवः pl.) n India: spring (वसन्त), summer (ग्रीष्म), rains (वर्षा), clear (शरद्), pre-winter (हेमन्त) and winter (शिशिर). Years can be reckoned from annual events (such as the equinoxes — when days and nights are of equal lengths), but it is more convenient in a lunisolar calendar to match the beginnings of years from lunar month boundaries.
The path of the sun across the sky (technically, the earth around the sun) as seen in front of the the background of the stars is called the zodiac (राशिचक्र) . Indian astronomers could calculate this to good precision as well, allowing them to predict the path of the sun as seen in the sky. The mean solar year was calculated to be approximately 365.24 mean solar days.
Naming the months
In a solar calendar, the usual practice is to name months after the constellation (राशि) in the zodiac (राशिचक्र) that the sun passes through in that month. The transit of the sun into a constellation (called सङ्क्रमण) marks a new month.
In an new-moon (अमान्त) lunisolar calendar, a month begins after a new moon, and is named after the asterism (नक्षत्र) associated with the next full moon, which depends on the position of the sun, and hence the equivalent solar month. A full-moon (पूर्णिमान्त) calendar month starts a fortnight before the corresponding अमान्त month. We assume the अमान्त system below unless specified.
- Chaitra (चैत्र): The first lunar month of the year, starts after the new moon preceeding the sun's transit into मेष (Aries)
- Vaishaakha (वैशाख) : The second lunar month, starts after the new moon preceding the solar transit into वृषभ (Taurus)
- Jyeshtha (ज्येष्ठ): Starts after the new moon preceding the transit into मिथुन (Gemini)
- Aashaadha (आषाढ़): Starts after the new moon preceding the transit into कर्क (Cancer)
- Sraavana (श्रावण): Starts after the new moon preceding the transit into सिंह (Leo)
- Bhaadrapada (भाद्रपद): Starts after the new moon preceding the transit into कन्या (Virgo)
- Aasvina (आश्विन): Starts after the new moon preceding the transit into तुला (Libra)
- Kaartika (कार्तिक): Starts after the new moon preceding the transit into वृश्चिक (Scorpio)
- Maargashiirsha (मार्गशीष): Starts after the new moon preceding the transit into धनुस् (Sagittarius)
- Pausha (पौष): Starts after the new moon preceding the transit into मकर (Capricorn)
- Maagha (माघ): Starts after the new moon preceding the transit into कुम्भ (Aquarius)
- Phaalguna (फाल्गुन): Starts after the new moon preceding the transit into मीन (Pisces)
The point of this unusual association of lunar month names with solar transits will become clear soon.
The catch
We now have a year with twelve months, and all should be well, but for a small catch: twelve mean lunar months (29.54 * 12 = 354.36) are about 11 days short of a mean solar year (365.24 days). This would mean that the association between lunar months and solar transits would slowly go out of synchronization.
Other cultures that have lunar calendars solve this problem by intercalation — the occasional insertion of extra (leap or intercalary) months. The Jewish calendar follows a Metonic Cycle where years 3, 6, 8, 11, 14, 17, and 19 of a 19 year cycle are 13 month years.
The Indian Lunisolar Calendar avoids fixed schemes of intercalation like the Metonic cycle. It includes an ingenious self-aligning intercalation system that is based on the association between Lunar month names and solar transits. As the cycle of 12 lunar months goes out of synchronization with the mean solar year, lunar months appear with no solar transits between two new moons, which are automatically designated extra (अधिक) months.
For example if the lunar month after चैत्र does not have a solar transit in it (which means the transit occurs in the month after that), both months can claim the name वैशाख. The first such month becomes अधिकवैशाख, and the second शुद्ध वैशाख. Relgious festivals, birthdays and such are not celebrated in the extra (अधिक) month, but in the following शुद्ध month.
This automatically keeps lunar months in sync with their solar counterparts.
Lost Months
While this intercalation scheme is ingenious, and self-correcting (think about it), it comes with a minor disadvantage — that of the occasional lost (क्षय) month. Since the earth's angular velocity around the sun is higher near perihelion, the “short” solar months of धनुस् (Sagittarius), मकर (Capricorn), and कुम्भ (Aquarius) , corresponding to मार्गशीर्ष, पौष, or माघ may be completely contained in a long lunar month, leading to two solar transits in a lunar month, one of which would then have to be “lost”.
Interestingly, this can only occur when there are months with no solar transits (अधिक) on both sides of such a two-transit (क्षय) month. Different variants of the Indian calendar treat this situation slightly differently
- In the Eastern calendars, the first अधिक month is treated as अधिक, the क्षय month is named after the first transit, and the following month is treated as a शुद्ध month named after the second transit in the क्षय month
- In the Northwestern calendrical tradition, the reverse is done. The first अधिक month is treated as a शुद्ध month named after the first transit, the क्षय is named after the second transit, and the third month is treated as an अधिक month
- In the Southern calendars, the क्षय month is called युग्म (dual), and is treated as being both the transits it has claim to. Months on both sides are considered अधिक months.
Putting it Together
We built up the Indian Lunisolar Calendar system thus:
- We have months based on phases of the moon, ending on new moon (अमान्त) or full moon (पुर्णिमान्त).
- There are twelve lunar months, from चैत्र (chaitra) to फाल्गुन (phaalguna), synchronized with the solar transits that occur in them.
- Months are divided into Dark (कृष्ण) and Light (शुक्ल) fortnights (पक्ष), which Amanta and Purnimanta months start with respectively.
- If a lunar month does not contain a solar transit, it automatically becomes an extra (अधिक) month. This takes care of the problem of intercalation without the need for a mechanical procedure like the Metonic Cycle.
- If a lunar month contains two solar transits (rare), it becomes a lost (क्षय) month. Treatment of such a month is different in Northwest, Eastern and Southern calendar traditions.
Festival Days
Now we approach the question that puzzles many an Indian:
Most festival days in India are determined by the Amanta calendar (even in regions which follow Purnimanta). For example:
- Maha Siva Ratri — 14th day of Maagha Krishna Paksha (माघ कृष्णपक्ष १४), and the preceding night.
- Holi — Phaalguna Purnima (फाल्गुन पूर्णिमा), the full moon day in the Phaalguna month
- New Year/Ugaadi — (चैत्र शुक्लपक्ष १) Chaitra Shukla Paksha 1 (Note — in Purnimanta calendars, Ugaadi doesn't coincide with the beginning of the year!)
- Buddha Purnima — Vaishaakha Purnima (वैशाख पूर्णिमा)
- Ganesha Chaturthi — Bhaadrapada Shukla Paksha 4 (भाद्रपद शुक्ल पक्ष ४)
- Mahanavami — Aashvina Shukla Paksha 9 (आश्विन शुक्ल पक्ष ९)
- Deepavali — Aashvina new moon (आश्विन अमावास्य)
Gujarat is a bit of an outlier as their New Year goes — they follow an Amanta lunisolar calendar, but start their year from Kaartika 1 or Aashaadha S 1 depending on which part of the state you look at.
Eras
Calendars usually start from a fixed (often legendary) event so as to be able to assign a sequential number to each year. Indian calendars follow two popular start points — Vikrama Samvat (57 BCE) and Shalivahana (Saka) Samvat (78 CE). Most of Northern India follows the former, while Southern India follows the latter. 2017 CE (post Ugadi) is therefore 2074 VS and 1939 SS.
Solar Calendars
What about states that follow Solar Calendars? More about them, Festivals tuned to the Solar Calendar (such as Vishu or Onam), and the tricky issue of Sidereal vs. Tropical calendars, or why the Vernal Equinox doesn't happen when you think it should in a later article, most likely around Solar New Year!
Happy Ugadi for VS 2074, or SS 1939!
