Why did the ancient Egyptians believe their Ibis God Thoth lived on the darkside of the moon?

Question

And why would a bird god need a flying ship ?

Answer 1

That's were all the aliens pretending to be gods were hiding, silly.

Answer 2

I think it was just the metaphoric for Thoth living in the DUAT, the Egyptian relm between the earth and the universe. What the ancients believed was that "sky-gods" were their first ancestors. More than likely refering to extraterrestrial contact. As to why a bird god would need a ship is probably the ancients associating how he first got here to the way he would return.