"Sizing Up The Universe" is a new National Geographic book on astronomy. While the book is loaded with many beautiful pictures, as one would expect from a National Geographic book, it also answers in some detail several fundamental questions: from small to big, what is out there in the universe, how big are those things, and how far away are they? In fact, the book does more than answer these questions; it explains how astronomers figured out the answers. To this end, the book starts with a survey of what we see when we look at the night sky, both with and without a telescope. It then explains in some detail how astronomers figured out how far away those things are starting with the Moon, the Sun, and the planets and extending to the farthest reaches of our visible universe. Finally, the authors take the reader on a "journey in scale" starting with size comparisons in our own Solar System and then progressively jumping up in size by factors of 1000 until the entire visible universe can be illustrated on a single page of the book.