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.

"A brief description of planets, including what they are, where they are, and how they orbit around the sun"--Provided by publisher.

In 2006, Pluto was reclassified as a dwarf planet. Small, rocky dwarf planets make their home on the outer edges of the solar system. Scientists use telescopes to study Pluto and the dwarf planets as they orbit the Sun. Their fascinating findings are on display in this informative title about some of the solar system’s most far-away objects!

In the cold, dark, lonely environment of the outer reaches of the Solar System lies Pluto, the smallest and most distant planet in the sun's family. Because it is so far away, Pluto remains largely mysterious. Yet in recent years astronomers have found important clues to its physical features, formation, and relationship with its single moon, Charon.

Describes Pluto, which was officially designated a dwarf planet in 2006.

Pluto looms large in Flagstaff, where residents and businesses alike take pride in their community's most enduring claim to fame: Clyde Tombaugh's 1930 discovery of Pluto at Lowell Observatory. Percival Lowell began searching for his theoretical "Planet X" in 1905, and Tombaugh's "eureka!" experience brought worldwide attention to the city and observatory. Ever since, area scientists have played leading roles in virtually every major Pluto-related discovery, from unknown moons to the existence of an atmosphere and the innovations of the New Horizons spacecraft. Lowell historian Kevin Schindler and astronomer Will Grundy guide you through the story of Pluto from postulation to exploration.

The New York Times bestseller: "You gotta read this. It is the most exciting book about Pluto you will ever read in your life." —Jon Stewart When the Rose Center for Earth and Space at the American Museum of Natural History reclassified Pluto as an icy comet, the New York Times proclaimed on page one, "Pluto Not a Planet? Only in New York." Immediately, the public, professionals, and press were choosing sides over Pluto's planethood. Pluto is entrenched in our cultural and emotional view of the cosmos, and Neil deGrasse Tyson, award-winning author and director of the Rose Center, is on a quest to discover why. He stood at the heart of the controversy over Pluto's demotion, and consequently Plutophiles have freely shared their opinions with him, including endless hate mail from third-graders. With his inimitable wit, Tyson delivers a minihistory of planets, describes the oversized characters of the people who study them, and recounts how America's favorite planet was ousted from the cosmic hub.