The position of Adhik Maas amongst the other months is variable, re-occurring about every 32.5 months. This is in contrast to some other common lunisolar calendars that insert an intercalary lunar month at a fixed point of the year. For example, in the Jewish calendar, the extra month is added before Adar; in the Buddhist calendar, it is added after Ashadha / Waso.
During 2015, Adhik Asadha (extra month before Asadha) was observed from 17 June to 16 July (south-west tradition, where month starts after new moon) or from 3 June to 2 July (north-east tradition, where month starts after full moon). In 2018, Adhik Jyaistha will be from 16 May to 13 June (or 30 April to 29 May if ending the months on the full moon).
The other names for Purushottam Maas are Adhik Maas, Mala Maas ('unclean month'), and Malimmacha. Spellings in the Latin alphabet vary, including purshottam, purushottam, purushottama; adhik, adhika; maal, māla; maas, maasa, mās, māsa, mas, mass. This is the thirteenth month of the lunar calendar. Adhik Maas adopts the name of the month that follows.
Purushottam Maas is considered inauspicious and no activities like weddings or moving into a new house are conducted. It is a time for prayer, fasting, charity, and self-improvement.
According to Vasishtha Siddhantha (the treatise of Vasishtha), Purushottam Maas or the extra lunar month occurs after every 32 months, 16 days and 8 ghati. (A ghati is 1⁄60th of a sidereal day, approximately 24 minutes, so 8 ghati is about 3 hours.) In this reference the concept of Adhik Maas is unique to the traditional Hindu lunar calendars. It is one of the most accurate methods to adjust the gap between Solar and Lunar Year.
When the Sun does not at all transit into a new rāshi (30° sidereal zodiac) but simply keeps moving within a rāshi in a lunar month (i.e. before a new moon), then that lunar month will be named according to the first upcoming transit. It will also take the epithet adhik or "extra". The transition of the sun from one rāśi to the next is called sankranti. For example, if a lunar month elapsed without a sankranti and the next transit is into Mesha (Aries), then this month without transit is labelled Adhik Chaitra. The next month will be labeled according to its transit as usual and will get the epithet nija ("original") or shuddha ("clean"), in this case Nija Chaitra. The terms Pratham (first) Chaitra and Dwitiya (second) Chaitra may also be used. Adhika māsa (month) is the first of two whereas an adhika tithi is the second of two.
Extra Month, or Adhika Māsa falls every 32.5 months on an average. It is also known as Puruśottama Māsa, it is said that the name was given by Lord Vishnu as his name to this month. The solar year is made up of 365 days and about 6 hours, and the lunar year is made up of 354 days. Thus there is a gap of 11 days, 1 hour, 31 minutes and 12 seconds between the lunar and the solar years. As this gap accumulates each year, it approximates in three years to one month. No adhik mas falls during Margsheersh to Magh. A case of Adhik Karttik is extremely rare, but in the 250-year span (1901-2150 AD) it would occur once, in 1964 AD.
The Moon takes about 27.3 days to make one complete orbit around the earth. The earth orbits around the sun once every 365.2422 days (= earth's orbital speed of 29.79 km per second). The earth and the moon in 27.3 days have moved as a system about 1/12 of the way around the sun. This means that from one full moon to the next full moon, the moon must travel 2.2 extra days before it appears again as a full moon, due to the curve of the earth's orbit around the sun. Ultimately this creates a variance of 10.87 days a year between a lunar year and a solar year. To compensate for this difference, the additional month is added after every 32.5 months on average.
Just as there are lunar years with the extra month making 13 total months, there are lunar years with a reduced number of months, with only eleven months in the particular lunar year. The lunar year with eleven months is very rare. It occurs once in 140 years or once in 190 years.
Religious significance of Adhik Maas
A month-long mela (fair) is celebrated in Machhegaun village in Nepal during Adhika Māsa. It is general belief that one can wash away all his sins by taking a bath in the pond at Machhenarayan temple.
Since this is a special month which does not come every year, there are no specific festivals like Dasara or Diwali in this month. Rather this month is treated as special and holy month and many people perform the adhik maas vrata. People perform extra mala japas, pradakshinas, pilgrimages, scriptural reading and parayans.
During Purushottam Maas, people perform various types of religious rituals such as keeping fast, recitation of religious scriptures, mantras, prayers, performing various types of puja and havan. Vratas (fasts) of various durations (full day, half day, weekly, fortnight, full month) are often undertaken. The vratas may be of complete fasting with liquids only or without liquids, fasting with fruits only or keeping fast with vegetarian food, as the individual can tolerate. It is said that the persons performing good deeds (satkarma) in this month conquer their senses (indriyas) and they totally come out of punar janam (the cycle of rebirth).
- Adhik Maas (Original source)
- Hindu Chronology, Encyclopædia Britannica Eleventh Edition (1911)
- The Astronomical Basis of the Hindu Lunisolar Calendar
- Hindu Calendars in various Indian Languages
- Adhik mass
- 12 important facts about Adhik Mass you must know!
- Examples of "sankranti" in use include , .
- See for example first (adik) Asada and second Asada at June