Gagan Mai Thaal is a hymn of Guru Nanak, the founder of Sikhism, sung as the Sikh aarti and included in the Guru Granth Sahib. Sikh tradition connects its composition with Nanak's visit to the great temple at Jagannath Puri, where, on being invited to join the ceremony of waving lamps before the image, he is said to have responded with this hymn, which reframes the whole cosmos as the act of worship: the sky is the platter, sun and moon the lamps, the stars the scattered pearls, the whole of nature performing aarti to the formless divine. In place of a rite offered to an image, the hymn presents the entire creation as continually worshipping its creator, expressing the Sikh insistence on a God without form who is not to be confined to an idol. It is sung in gurdwaras, especially in the evening, and stands as one of the most celebrated expressions of Nanak's teaching, at once a hymn of wonder at creation and a gentle reorientation of the meaning of worship itself.
The hymn is traditionally read as a direct, gentle challenge to the Puranic aarti ceremony Nanak is said to have witnessed at Puri, replacing an act performed by human hands before a physical image with an image of the cosmos itself perpetually worshipping a God who has no physical form to receive an offering. It is sung today as part of evening devotional gatherings, and its imagery of the whole of nature as a single unceasing act of worship has made it one of the most frequently quoted of Guru Nanak's compositions outside its immediate liturgical setting.