The calendar

The Hindu lunar year: masas, ritus and the samvatsara cycle

Chaitra to Phalguna with their Telugu names, the six ritus, how the sixty-year samvatsara cycle works, and why an extra month has to be inserted every three years.

The Hindu calendar is luni-solar, which is a compromise and an honest one. Months follow the moon, because the phases are visible to everyone and need no instrument. The year follows the sun, because the seasons do. Those two cycles do not divide evenly into one another, and most of the structure below exists to reconcile them.

The twelve masas

A masa is a lunar month. It is named for the nakshatra in which the full moon of that month falls — Chaitra for Chitra, Vaishakha for Vishakha, and so on down the list.

In the Telugu country these are the same twelve, and the year opens with Chaitra at Ugadi. The name Ugadi is yuga-adi — the beginning of an age — and the day is kept as the start of the new samvatsara.

Two ways to cut the month

Where a month begins depends on region. Amanta reckoning ends the month at the new moon and is used across the south and west, including the Telugu states. Purnimanta reckoning ends it at the full moon and is used across most of the north. The two agree on every waxing-fortnight day and differ by one month name on every waning-fortnight day. This is the single most common reason two panchangams appear to disagree, and it is a naming difference rather than a date one.

Adhika masa: the correction

Twelve lunar months come to about 354 days. A solar year is about 365. Left uncorrected, the calendar would drift eleven days a year and Ugadi would migrate through the seasons, arriving in winter within a few decades.

The correction is an extra month, adhika masa, inserted roughly every thirty-two and a half months. The rule that decides when is elegant: a lunar month containing no solar sankranti — no moment at which the sun enters a new rashi — is intercalary. Because a lunar month is about 29.5 days and a solar month about 30.4, most lunar months contain exactly one sankranti; occasionally one slips through containing none, and that is the month that repeats.

• The intercalary month takes the name of the month that follows it, prefixed adhika. The real one is then nija — 'true'.
• Festivals are observed in the nija month, not the adhika one.
• Monthly vratams occur in both, which is why an adhika masa year has twenty-six Ekadashis rather than twenty-four.
• Adhika masa is also called mala masa or purushottama masa, and is treated as unsuited to weddings and other auspicious beginnings — though it is regarded as excellent for practice and charity.

The opposite case exists and is far rarer: a kshaya masa, a month that contains two sankrantis and is therefore dropped. It occurs only around Margashira, Pushya and Magha, and only about once a century.

The six ritus

Two masas make a ritu. Six ritus make the year, and they map onto the actual weather of the subcontinent far better than a four-season scheme does.

Uttarayana and dakshinayana

The solar year is also cut in two by the direction of the sun's apparent motion. Uttarayana is the northward course, beginning at Makara Sankranti when the sun enters Makara; dakshinayana is the southward, beginning at Karka Sankranti. Uttarayana is regarded as the more auspicious half and carries most of the wedding season.

One historical note worth having, because it explains a real confusion. Makara Sankranti is a sidereal event — the sun entering the sidereal Makara — and it now falls around 14 January, whereas the actual winter solstice is around 21 December. The two coincided roughly seventeen hundred years ago and have separated since through precession. The festival tracks the sidereal position, not the solstice.

The sixty-year samvatsara cycle

Years themselves are named, in a repeating cycle of sixty, beginning with Prabhava and ending with Kshaya. The cycle derives from the near-coincidence of five Jupiter orbits with sixty solar years — Jupiter takes about twelve years to circle the zodiac, so sixty years is five complete circuits.

This is why an elder will name the year they were born as a word rather than a number, and why the same name returns once in a lifetime. In the Telugu states the new samvatsara begins at Ugadi, and the Panchanga Sravanam — the public reading of the year's panchangam — is the ceremony that announces it.

Putting it together

A fully specified Hindu date names the samvatsara, the ayana, the ritu, the masa, the paksha, the tithi, the vaara and the nakshatra. That is the sankalpa formula recited before any ritual — and it is not ceremony for its own sake. It locates the moment against the sun, the moon and the sixty-year cycle simultaneously, which is precise enough to be unambiguous without a single number in it.

Every timing referenced in these guides is computed astronomically for the city you select and cross-referenced against the traditional panchangams in common use. How we compute