Mahalaya Amavasya is observed on Amavasya during Ashwin month as per North Indian calendar followed in Uttar Pradesh, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Himachal Pradesh, and Uttaranchal. Pitru Amavasya is the last day of Pitru Paksha, the fortnight dedicated to offer Shraddh rituals to dead ancestors.
Mahalaya Amavasya is great significance to Hindus because on this day Hindus perform Shraddh karma to Pithru devatas or dead ancestors. The dark fortnight in Ashwina month is observed as Mahalaya Paksha. Ashwin Amavasya is the day to propitiate the spirits of ancestors with shanty mantras (prayers for peace). Shraddh rituals performed on Mahalaya Amavasya are considered as equal to that of Shraddh rituals performed at Gaya.
During Mahalaya Paksha Sun enters the sign Virga (Kanya) and on Mahalaya Amavasya a conjunction of Sun and Moon occurs. As per the Hindu beliefs, on this auspicious day, dead ancestors leave their place and arrive to our world and live in the houses of their descendants. On this day, Hindus offer food to the Brahmin and poor people. The food offerings and other charity reach the departed souls and the dead ancestors pleased with the charity of their descendants and bless them with longer and healthy life.