Recently, astronomers have demoted Pluto from full planet status, leaving only eight remaining planets in our solar system. This text deals with this scholarly debate and even records the discovery of possibly another planet, which is larger than our moon. However, this book was published before Pluto became a non-planet so it does not report the final proclamation. The preface gives a brief historical overview of human observation of the skies. It also defines rotation, inclination, and obliquity and the different features of the planets. The introduction touches upon some common misconceptions about the planets in the outer solar system and gives a taste of what will be covered in the following chapters. The chapters deal with Uranus and its gravity, interior composition, internal temperatures, elements, isotopes, magnetic field, surface temperature, conditions on the surface, its rings and moons. Another chapter covers Neptune and its interior, surface appearance, conditions on the surface, its rings and moons. The following chapter talks about Pluto and the Kuiper Belt, Pluto's orbit, Pluto's interior, and the debate about whether Charon is Pluto's moon or its companion planet. The final chapter covers space beyond the Kuiper Belt, the Oort Cloud, and some conclusions about the known and the unknown. Except for a small block of color photographs in the middle of the book, all the diagrams and photographs are in black-and-white. The type is small but the page design allows for lots of interesting images, diagrams, and charts to add interest. This book is part of Chelsea House's "The Solar System" series, which includes the titles Asteroids, Meteorites, and Comets; The Earth andthe Moon; Jupiter and Saturn; Mars; The Sun, Mercury, and Venus; and Uranus, Neptune, Pluto, and the Outer Solar System. Each title contains extensive back matter, including an index for both subject and illustrations; a list of organizations of interest; a glossary; a list of Internet resources; a bibliography; charts and tables for light, wavelength, and radiation measurements; and a list of all known moons. An appendix for units and measurements covers the fundamental units; compares Kelvin, Celsius, and Fahrenheit; lists the useful measures of distance; gives the definitions for electricity and magnetism; and lists some common prefixes.