It's a kind of invocation or invitation to the mother goddess to descend on earth. This is done through the chanting of mantras. The day is being observed as Mahalaya, the day of invocation. In the dark night of amavasya (new moon), people pray to Goddess Durga to arrive in the earth to ward off all evils.

On this auspicious day, people pray for the deceased relatives and take holy dip in the river Ganga - the act being called Tarpan. On the dawn of Mahalaya, homes in Bengal resonate with the immortal verses of the Chandipath (chanting from "Chandi"). Chanting of the hymns from the holy book of "Chandi" in the recorded voice of late Birendra Krishna Bhadra over radio has become synonymous to the real Chandipath. The Chandipath is aired by All India Radio in the programme Mahisasura Mardini, narrating the incarnation of Goddess Durga and her fight with Mahishasura. Since the early 1930s, Mahalaya has come to associate itself with an early morning radio program called "Mahishasura Mardini" (the annihilator of the demon Mahishasura). This All India Radio (AIR) program is a beautiful audio montage of recitation from the scriptural verses of "Chandi", Bengali devotional songs, classical music and a dash of acoustic melodrama. The program has also been translated into Hindi set to similar orchestration and is broadcast at the same time for a pan-Indian audience. For nearly six decades now, the whole of Bengal rises up in the chilly pre dawn hours, 4 am to be precise, of the Mahalaya day to tune in to the "M Chandipath narrates that She is the primeval source of power, all qualities reside in her. She is one and yet known by many names. She is Narayani, Brahmani, Maheshwari, Shivaduti and She is the fierceful Chamunda, decked with a garland of skulls. The Goddess Chandika is eternal. She has no birth, no definite physical form. She assumes a manifestation of majestic might only to restore the process of Creation from the terrible Asuras or evil incarnates. Mahisasura, the terrible king of the Asuras had defeated the gods and driven them out of Heaven. The gods, dejected and humiliated went to Brahma, the god of creation Vishnu, the God of preservation and Mahadeva, the God of destruction, to report their defeat. These three Gods projected their energy and evoked a new form of energy. This energy then crystallised into the heavenly form of a Goddess. She was Mahamaya, the Mother of the Universe. The emergence of the goddess was an auspicious moment. The Goddess then emerged in full battle array to combat Mahisasura. The Himalayas gifted Her the lion to act as her carrier, Vishnu gave her the Chakra , Mahadeva gave her the trident, Yama gave her the danda, Brahma gave her the rosary and the container of sacred water. Armed with weapons of all kinds, the Mother Goddess defeated the Asuras, thus ending the rule of evil forces. The occasion of Mahalaya, thus, always goes on reminding mankind of the divine scheme of things that the Evil may have had its say, but it is ultimately the Good that has the last laughahishasura Mardini" broadcast.