I was born on a Monday on the 6^th day of the Bengali month Kartik and 23rd day of the English month October. Somehow 6^th Kartik and 23^rd October have rarely coincided since then. As we follow the English calendar or the Georgian calendar 23^rd October is my birthday, I don’t even know when 6^th Kartik comes and goes. My mom who keeps a track of Bengali dates sometimes casually mentions “Oh, today’s 6^th Kartik, your birthday.” So long it never bothered me why the Bengali and the English dates didn’t match.

Even our festivals never fall on the same dates. I was born on the day after Lokhhi pujo (Kojagori Lokkhi who is worshipped a week after Dashami or Dussehra). Since then, my birthday every year coincides with either Durga Puja, Dussehra, Diwali or comes very close to one of these festivals. In fact, our festivals don’t fall on the same dates every year even in the Bengali or Hindu calendar. That is because we track time as per movements of the sun, moon and the stars. These religious festivals take place only when the stars are aligned in their right planetary position. We Bongs refer to Panjika or the Hindu Almanac for the same.

Panjika or Panji is the Hindu astronomical almanac published in Bengali, Odia, Maithili and Assamese. Called Panchangam in other parts on India, it is published annually and is a handy reference to determine the most auspicious times for our rituals, festivals, celebrations, marriages etc. Panjika also records Muslim, Christian and other festivals, dates of birth and deaths of many leading personalities and carries informative articles on astrology. Panjika applies 2 methods for calculation of planetary positions – Surya Siddhanta and Bisuddha Siddhanta.

To understand the discrepancies in dates in different calendars, it is important to understand how we track time. Our forefathers observed the movements of sun, moon and other planetary bodies for timekeeping. The Georgian calendar, that is now followed world over, is based on the movement of the earth around the sun. It was introduced in October 1582 by Pope Gregory XIII as a minor modification of the Julian calendar, reducing the average year from 364.25 days to 364.2425 days. Therefore, every 4^th year is the leap year.

Many religions and cultures, like the Islamic culture and Asian countries like China, Hong Kong and Vietnam, follow the lunar calendar. A lunar calendar is a calendar based on the monthly cycles of the Moon’s phases. Since each lunation is approximately ​29 ¹⁄₂ days (29 days, 12 hours, 44 minutes, 3 seconds, or 29.530588 days), the months of a lunar calendar usually alternate between 29 and 30 days. A lunar year is only 354 days, 8 hours, 48 minutes, 34 seconds (354.367056 days), hence purely lunar calendars lose around 11 to 12 days per year relative to the Gregorian calendar. 

The Vedic culture developed a sophisticated timekeeping methodology and calendars for Vedic rituals. Timekeeping was about tracking the nature of solar and lunar movements and other planetary bodies. Timekeeping was important to Vedic rituals, and Jyotisha or astrology tracked and predicted the movements of astronomical bodies in order to keep time and fix the date and time of different rituals.

The Hindu calendar that was derived from the Vedic tradition is lunisolar calendar, traditionally used in the Indian subcontinent and South-east Asia, with further regional variations for social and religious purposes. The calendar adopts a similar underlying concept for timekeeping based on the solar cycle and adjustment of lunar cycles every three years. Unlike the Gregorian calendar which adds additional days to the lunar month to adjust the mismatch between twelve lunar cycles (354 lunar days) and nearly 365 solar days, the Hindu calendar maintains the integrity of the lunar month, but inserts an extra full month by complex rules, once every 32–33 months, to ensure that the festivals and crop-related rituals fall in the appropriate season.

There’s also an argument about the accuracy about the different methods of timekeeping. While the Georgian calendar being easier to follow is widely accepted, some believe that the Lunisolar calendar could be more accurate. But, accuracy, I feel, is a matter of perspective. Different calendars follow different methods of timekeeping, hence the discrepancies. It doesn’t make one right and the other wrong. Though it’s easy to think of time as linear and calendar as scientific given, these different calendars show us that time is anything but linear. It’s relative, keeping time is complicated. Modern timekeeping devices that accurately measure time even to the fraction of a second, have been invented to give us the impression that we are in control while time is slipping away!