Invoking goddess Durga on earth, West Bengal on Tuesday observed Mahalaya with devotional songs, scriptural recitations and prayers as greetings on social media enlivened a rainy day.Celebrated a week before the five-day Durga puja begins, Mahalaya essentially heralds the homecoming of the goddess.Mahalaya signifies the end of Pitri Paksha (the period when Hindus pay homage to their ancestors) and the beginning of Debi Paksha (period of the goddess).Sheltered under umbrellas against the rain, thousands thronged the banks of river Hooghly -- palms clasped in prayers -- with the break of dawn to carry out special rituals called "Tarpan", in honour of their ancestors.According to tradition, the sons offer food and prayers in the belief that the souls of the departed would smoothly make their transition to heaven.Mahalaya is culturally synonymous with the iconic early morning broadcast of "Mahishasura Mardini" (the annihilation of the demon) invocation on All India Radio in the sonorous voice of Indian playwright and broadcaster Birendra Krishna Bhadra.Following an over eight decade old ritual, Bengalis and even many non-Bengalis tuned in to the recordings of Bhadra's haunting voice, narrating the arrival of the goddess and the fierce combat between Durga and the Asura (demon) resulting in the slaying of the demon with the goddess's trident.Peal of temple bells - echoing across neighbourhoods as devotees offered prayers - added to the fervour. Dressed to the nines, residents scurried around crowded market places to wrap up the last spot of shopping with only a week left to go for the mega event. Most enjoyed their day-off with food binges -- both traditional home-cooked food, as well as gourmet spreads at restaurants.With attractive discounts, online shopping sites remained the top draw.Cloaked in plastic sheets, at the potters' enclave in Kumartuli in north Kolkata, artisans worked frantically to give finishing touches to idols of the goddess while puja organisers hurried to put together the marquees (pandals) for inaugural.West Bengal Chief Minister Mamata Banerjee took to Twitter to wish everyone on Mahalaya.According to Hindu mythology, goddess Durga, accompanied by her four children -- Ganesh, Kartik, Lakshmi and Saraswati -- descends to earth every year to visit her parents. That is when Puja is celebrated.Durga, it is believed, stays for five days to eradicate evil from earth before returning to her husband, Lord Shiva, at Kailash on Dashami (the 10th day). Durga, the slayer of the demon Mahishasur, sits astride a lion and wields an array of weapons in her 10 hands.