An aarti is a devotional ritual that uses fire as an offering. It's usually made in the form of a lit lamp, and in the case of the Ganges River, a small diya with a candle and flowers that's floated down the river. The offering is made to the Goddess Ganga, also affectionately referred to as Maa Ganga, goddess of the holiest river in India. The aartitakes on special significance on the auspicious occasion of Ganga Dussehra,when Maa Ganga is believed to have descended from to heaven.