For the first time, Maa Durga will be worshipped 35 days after Mahalaya, which marks the beginning of Devi-Pakshma and end of Pitri-Pakshma, next year. Normally, Mahalaya is observed seven days before the Durga Puja. Next year, Mahalaya is scheduled on 17 September, the day when Biswakarma Puja is observed every year, and Mahasashthi is on 22 October. The usual gap between Mahalaya and Mahasashthi, the first day of the Durga Puja festival, is six days.

This unusual schedule is unheard before. In 2001, Durga Puja was observed 30 days after the Mahalaya. Bisuddha Siddhanta and Suryasiddhanta, both schools of almanacs, agree on the unusual schedule. According to the two schools, the rare aberration happens because of the occurrence of a phenomenon called mala mash, a lunar month which has two new moons (amavasya). No auspicious rites and rituals can be performed in a mala mash. Next year, Bengali month Ashwin is a mala mash and for this reason Durga Puja will be deferred till the amavasya (lunar month) is over. And the Puja will be held next month, that is Kartik, according to the almanacs.

Pitritarpan (offerings to ancestors) and other rites slated for Mahalaya will take place as usual on the morning of 17 September, the first day of Ashwin, which falls on amavasya. Ashwin’s second new moon will be on the 29th day of the month that is on 16 October. This is the second time that this unusual schedule is happening in the 21st century, the last occurrence being in 2001 when the dates had coincided with what they will be next year – Mahalaya on 17 September and Mahasashthi on 22 October. Before that, the phenomenon had happened in 1982.