A man named Vidfinn had two children named Hjuki and Bil. He sent them to the well Byrgir to fetch a cask of water. When Mani saw the two children he took them away with him to the moon. The two children, together with their cask and pole, can be seen on the face of the moon (the moon spots).
In Norse myth, Mani is the personification of the moon, son of Mundilfari and brother of Sol, the sun. At night he rides a chariot pulled by horses through the sky, and determines its waxing and waning. Mani is chased by the wolf Hati ("hate"). Whenever the wolf managed to catch the moon, a lunar eclipse would take place. This caused great consternation, and by making a lot of noise people tried to scare the wolf away.
This myth is said to be the origin of the nursery rhyme about Jack and Jill.