Why is the sky blue? How do astronauts breathe in space? What is a lunar eclipse? The Do You Know?™ books provide an in-depth look at a wide range of popular subjects. Appealing to children who want to know everything, each thought-provoking book features: 80 pages of informative content and answers to many popular questions, hundreds of labeled, full-color illustrations, an index to key terms and a "More to Know" section that motivates children to explore further.