Poet laureate Carol-Ann Duffy has written a suitably poetic, bedtime joke here. Humorously, beautifully and accurately (by which I mean matching the text) illustrated, the book is a poem about the zoo creatures of the Moon having dinner and going to sleep. The carefully developed joke is that of course zoo creatures cannot live on the Moon, but if they did, what would it be like? Starfish and chips, served by an alien Zookeeper! The poem has an unusual metre that creates a gentle atmosphere and the words will linger on in your mind after your child has long dropped off to sleep. This children’s picture book is suitable for three year-olds and up, I’d say, because younger children may not get the joke and also may not be familiar with concepts like gravity and the names of the planets. Another book by the same author makes a parallel joke about farm animals under the sea. In my opinion Underwater Farmyard is slightly more charming and easier to explain but there’s more to learn from Moon Zoo.