ಅಧಿಕ ಮಾಸ: ಹೆಚ್ಚುವರಿ ಮಾಸ | Adhika masa: the extra month

Twelve lunar months come to about 354 days. The solar year is about 365. Left alone, the lunar months would slide backwards through the seasons by eleven days a year, and within sixteen years Deepavali would fall in what is now the monsoon.

The correction is an extra month, the adhika masa, also called malamasa or purushottama masa. It is inserted roughly every thirty-two and a half months, which works out to seven times in nineteen years.

How it is detected

The rule is precise and requires no table. A lunar month takes its name from the zodiac sign the sun occupies at the new moon that begins it. Normally the sun changes sign once during each lunar month, so each month gets a distinct name.

Occasionally a lunar month passes with no solar ingress at all: the sun enters a sign just before the month begins and does not enter the next until just after it ends. That month has no name of its own, so it borrows the name of the month that follows and is marked adhika. The following month is then called nija, the true one.

This happens when the sun is moving at its slowest, which is near aphelion in early July, so intercalary months cluster around the middle of the year. Adhika Ashadha, Shravana and Bhadrapada are common; adhika Margashira, Pushya and Magha essentially never occur.

The opposite case

Very rarely the sun changes sign twice within one lunar month, and a month name is skipped entirely. This is a kshaya masa, a lost month, and it only happens when the sun is moving fastest, near perihelion in January. It last occurred in 1963 and 1983 and will not occur again until well into this century. A kshaya masa is always accompanied by two adhika masas in the same year.

What is set aside

The intercalary month is treated as unsuitable for auspicious beginnings: weddings, betrothals, house entry, the first feeding of a child, the start of a new business. Annual festivals and shraddha are kept in the nija month rather than the adhika one, which is why a festival does not occur twice in such a year.

The month is not regarded as inauspicious in itself. It is called purushottama masa, and it is considered well suited to recitation, charity, pilgrimage and fasting. The tradition is that Vishnu accepted the otherwise unclaimed month as his own.

The two Ekadashis that fall in an adhika masa carry names used nowhere else: Padmini in the bright fortnight and Parama in the dark.