Nut, in Egyptian religion, a goddess of the sky, vault of the heavens, often depicted as a woman arched over the earth god Geb. Most cultures of regions where there is rain personify the sky as masculine, the rain being the seed which fructifies Mother Earth. In Egypt, however, rain plays no role in fertility; all the useful water is on the earth (from the Nile River). Egyptian religion is unique in the genders of its deities of earth and sky. As the goddess of the sky, Nut swallowed the sun in the evening and gave birth to it again in the morning.

From Encyclopedia Brittanica