Why is Vishwakarma Puja celebrated on a fixed date – September 17?

Vishwakarma Puja, or Vishwakarma Jayanti, is celebrated annually on September 17 or September 18 in Bengal, Orissa, Jharkhand, Assam, Tripura and other parts of Eastern India. Majority of the Hindu festivals are not celebrated on a constant date because most auspicious days and festivals depend on the lunar calendar and on tithi – lunar day, which changes annually. But majority of times Vishwakarma puja falls on September 17 (very rarely it might vary by a day).

This is because Vishwakarma Puja day is calculated based on the transit of the sun. The two major schools of almanacs followed in Bengali are the he Surya Siddhanta and Bisuddha Siddhanta. Both subscribe to the same view.

Vishwakarma Puja is dedicated to Lord Vishwakarma the divine architect of the universe in Hinduism.

Sudeshna Banerjee writes about this interesting aspect in The Telegraph, Calcutta.

“Vishwakarma puja is scheduled on the last day of the Bengali month of Bhadra, more specifically on Bhadra sankranti. That is when the sun transits from Singha (Leo) to Kanya (Virgo) sign,” explains Pulak Bhattacharya of Gupta Press, the 139-year-old almanac that follows Surya Siddhanta.

There are usually 156 days of the Bengali year in the five months before Vishwakarma puja, calculates Bhattacharya.

In some years, one of the five months may have a day more or less because the number of days in the Bengali month fluctuates between 29 and 32. That is when the last day of Bhadra gets pushed back or forward by a day.

A scan of the last two decades of almanacs at the Gupta Press library revealed just two years when the puja has happened a day later — on September 18.

“The sun’s transit into Virgo is what determines the puja date for us, too,” adds Manoj Lahiri, who subscribes to Bisuddha Siddhanta.

A similar theory is followed in celebrating New Year and Pongal in Tamil Nadu and Vishu in Kerala.