This book is part of a book series called Seven Wonders .

This book has been graded for interest at 10-14 years.

There are 80 pages in this book. This book was published 2011 by Twenty-First Century Books (Tm) .

D. J. Ward is a high school science teacher who also writes science books for children. His titles include Exploring Mars, Materials Science, and another book in the Let's-Read-and-Find-Out Science series, What Happens to Our Trash? He lives in Castle Rock, Colorado. Paul Meisel has illustrated many books for children, including Why Are the Ice Caps Melting?, Energy Makes Things Happen, and What Happens to Our Trash? in the Let's-Read-and-Find-Out Science series. He lives in Newtown, Connecticut.