The sun has been shining for billions of years. It will continue to shine for billions more because its mass is fed by the energy of countless gas molecules. It is a huge hydrogen bomb, continually exploding, yet held together by gravity.

Isaac Asimov explains clearly and simply how the sun and planets were formed and how the sun’s energy is radiated to light and warm our earth. He gives readers a graphic introduction to the chemical and physical structure of the solar system and the earth’s place in it. There is a beautiful logic to his definition of such basic phenomena as radiation, energy, and molecular structure.

Dr. Asimov, a biochemist, has an unquenchable curiosity about countless scientific subjects and is a prolific writer of books about them.

This book is exceptional for a number of reasons. For one, it’s one of Asimov’s very rare science juveniles for grade school children not a part of a series such as the ABC books or the “How Did We Find Out” series or “Isaac Asimov’s Library of the Universe.” (It is part of a series—it’s just that the other books in the series are by other people.) For another, it’s one of the few Asimov books aimed specifically at a very young audience which I nonetheless look forward enthusiastically. I’m not sure why. Marc Brown’s delightful illustrations are a help, of course—but I think it’s mostly reading a book which manages to make stellar evolution and nuclear fusion so clear and straightforward that even a six-year-old can understand them. That’s not a minor feat, and it’s that, I think, that makes this book so enjoyable for me to read.

(Brown, by the way, is himself well-known as the author of the Arthur books which have successfully made the transition to public television, much to the delight of my youngest daughter.)