Moon! is an Elmo's World board book in which Elmo visits the Moon. The book is part of a set of four Elmo's World books about space; each book features photos of Elmo set against photos of outer space provided by NASA. The other books in the set are Spaceship!, Stars! and Sun! A squeak toy of the moon is built into the book, appearing through a hole on each page, with the reader instructed to squeak it when the word "moon" appears. A bath toy version of the book (and the other titles in the series) was released by Modern Publishing in 2012.