No matter which side of the debate you find yourself on, Is Pluto a Planet? will equip you with all the information you need to win your argument. And along the way, David Weintraub treats you to a fascinating tour of the past, present, and future of our attempts to understand the solar system and our place within it. -- Neil deGrasse Tyson, Astrophysicist at the American Museum of Natural History and Director of the Hayden Planetarium, New York City Is Pluto a planet? Sure it is. But is it a major planet like Mars and Jupiter, or is that distant tiny body more in league with Ceres, long ago catalogued as the first and largest of the minor planets? What degree of 'planethood' should be conferred on an object orbiting a star--too small to be a star itself, yet big enough to be round? With these stimulating questions (and more) in mind, I fully support Weintraub's conclusion that our youngsters get short shrift by learning only a simple mnemonic aid when introduced to the planets around our sun. -- Brian G. Marsden, Harvard-Smithsonian Center for Astrophysics David Weintraub tells a coherent tale with an ingenious story line. Well written and convincingly presented, Is Pluto a Planet? will appeal widely to general readers. It covers a topic that has exploded in the past decade, but I do not know of any other popular account of the outer solar system. -- Owen Gingerich, Harvard-Smithsonian Center for Astrophysics, author of "The Book Nobody Read: Chasing the Revolutions of Nicolaus Copernicus" General readers interested in the Pluto controversy will find much of interest in this book, which shows how the concept of 'planet' has evolved throughout history. As a professional interested in this topic, I found the historical narrative quite illuminating and useful. -- Gibor Basri, University of California, Berkeley and Co-Investigator, NASA's Kepler Mission

A Note from the Author: On August 24, 2006, at the 26th General Assembly of the International Astronomical Union (IAU) in Prague, by a majority vote of only the 424 members present, the IAU (an organization of over 10,000 members) passed a resolution defining planet in such a way as to exclude Pluto and established a new class of objects in the solar system to be called "dwarf planets," which was deliberately designed to include Pluto. With the discovery of Eris (2003 UB313)--an outer solar system object thought to be both slightly larger than Pluto and twice as far from the Sun--astronomers have again been thrown into an age-old debate about what is and what is not a planet. One of many sizeable hunks of rock and ice in the Kuiper Belt, Eris has resisted easy classification and inspired much controversy over the definition of planethood. But, Pluto itself has been subject to controversy since its discovery in 1930, and questions over its status linger. Is it a planet? What exactly is a planet? Is Pluto a Planet? tells the story of how the meaning of the word "planet" has changed from antiquity to the present day, as new objects in our solar system have been discovered. In lively, thoroughly accessible prose, David Weintraub provides the historical, philosophical, and astronomical background that allows us to decide for ourselves whether Pluto is indeed a planet. The number of possible planets has ranged widely over the centuries, from five to seventeen. This book makes sense of it all--from the ancient Greeks' observation that some stars wander while others don't; to Copernicus, who made Earth a planet but rejected the Sun and the Moon; to the discoveries of comets, Uranus, Ceres, the asteroid belt, Neptune, Pluto, centaurs, the Kuiper Belt and Eris, and extrasolar planets. Weaving the history of our thinking about planets and cosmology into a single, remarkable story, Is Pluto a Planet? is for all those who seek a fuller understanding of the science surrounding both Pluto and the provocative recent discoveries in our outer solar system.