Yeah, you could joke about her name, but she's heard it all before: the ancient Egyptian sky goddess has been around a loooong time. She married the earth god Geb and was happily pregnant with their kids when bam: prophecy time. It was foretold that one of their children would displace Ra, the sun god and the king of the gods. So Ra forbade Nut to give birth on any day or night of the year.
Luckily, our Nut is a resourceful goddess. She tricked the moon god Khons out of enough moonlight to create five new days to tack on to the existing year. Those days, the Demon Days, are when she gave birth to Osiris, Horus, Set, Isis, and Nephthys. But Ra punished Nut, anyway, by exiling her to the sky, while Geb is confined to the earth. Was the sacrifice worth it? Nut's saddened by the loss of her husband, but she seems to think it was.
When Sadie finally gets to meet Nut, she's stunned by her appearance: "[H]er skin was dark blue, covered with stars. I don't mean painted stars. She had the entire cosmos living on her skin: gleaming constellations, galaxies too bright to look at, glowing nebulae of pink and blue dust. Her features seemed to disappear into the stars that shifted across her face. Her hair was long and as black as midnight" (20.21). But then, why should the sky goddess be anything less than spectacular?