There is no superstition behind Adhik Maas (commonly known as 'Malmaas' or 'Purushottam Maas'); rather, pure science and astronomy lie at its roots.
To understand this mystery in simple words, we must understand the difference between the two main calendars: the Solar Calendar and the Lunar Calendar.
1. The Mathematical and Astronomical Difference
The Earth revolves around the Sun, and the Moon revolves around the Earth. There is a slight difference in their orbital timings:
- Solar Year: It takes the Earth approximately 365
days, 5 hours, 48 minutes, and 46 seconds (about 365.25 days) to
complete one revolution around the Sun.
- Lunar Year: A lunar month (from one new moon
to the next) lasts about 29.5 days. Based on this, a lunar year of 12
months lasts approximately 354 days.
The Main Problem: If you look at the difference between the two: 365 Days (Solar Year) - 354 Days (Lunar Year) = 11 Days This means that every year, the lunar calendar falls 11 days behind the solar calendar.
2. The Situation Created Every Three Years
If this 11-day difference is left as it is, it adds up to 33 days (nearly a full month) in just 3 years. If this continues indefinitely, the synchronization between our festivals and seasons would completely break down. (For example, Janmashtami or Diwali, which occur during the monsoon/autumn, would gradually start falling in summer or winter!)
To fix this discrepancy, an incredible astronomical calculation has been integrated into our Indian almanac (Panchang) system:
- Every 32 months, 16 days, and 8 hours, this gap adds up to exactly one month (30 days).
- As soon as this period is reached, an extra month is added to the lunar calendar, which we call Adhik Maas (Extra Month).
- Generally, Adhik Maas occurs once every 3 years (or 36 months).
3. The Science of 'Sankranti'
From an astronomical perspective, when the Sun moves from one zodiac sign into another, it is called a 'Sankranti'.
- Normally, the Sun changes its zodiac sign once every lunar month (such as Makar Sankranti, etc.).
- However, during the month that becomes the 'Adhik Maas', the Sun does not enter any new zodiac sign at all. In other words, no Sankranti occurs during that month.
- Scientifically, this 'zero-Sankranti' month is designated as 'Adhik Maas' to perfectly realign our calendar with the seasons and the movement of the Sun.
In Summary:
Just as the Western (Gregorian) calendar adds one day to February every 4 years to offset a 6-hour annual deficit—creating a 'Leap Year'—the Indian Panchang features a 'Leap Month' (Adhik Maas) every 3 years to offset the 11-day annual difference.
This is a magnificent example of the absolute mastery over mathematics held by the sages, saints, and astronomers of our ancient Sanatan culture.
