When Is a Planet Not a Planet?: The Story of Pluto

Scott takes the 2006 downgrading of Pluto from planet to dwarf planet as a teachable moment for discussing  questions such as how the number of planets has changed through the centuries, what can be called a planet, and how scientists come to conclusions and occasionally change their minds. Following a section on early astronomy, a succinct, timely, and somewhat surprising account of planetary history begins with Herschel's 1781 discovery of the seventh planet, Uranus. Twenty years later, Piazzi found Ceres, which was considered the eighth planet. In 1846, Galle discovered Neptune, bringing the total to nine. When objects similar to Ceres were found in the same orbit, all (including Ceres) were placed in a new category: asteroids. In other words, even before the discovery of Pluto, there were once nine planets, but one of them was demoted. Beautifully designed, the book includes many well-captioned, color illustrations, from period portraits to NASA images to artist's conceptions. A glossary and lists of recommended books and Web sites are appended. A good choice for updating astronomy collections.--Phelan, Carolyn Copyright 2007 Booklist

Gr 3-6--Many people were shocked at Pluto's demotion from a planet to a dwarf planet. How could it be a planet one day, and then not a planet the next? This exceptional book (Clarion, 2007) by Elaine Scott explains exactly why the change took place. She leads readers through a brief history of astronomy, starting with the ancient Greeks and moving up to Ptolemy, Copernicus, Galileo, Kepler, Newton, and modern astronomers. As she aptly points out, our views of the universe have changed many times as our knowledge base has expanded, and future changes are inevitable. The scientific process is presented, and the thinking behind the new definitions is carefully explained, as are the definitions themselves. In this recorded version of the book, Pete Larkin reads Scott's informative text with a rich voice. "Space Fact" boxes, as well as the glossary, are read by a female voice to give them distinction. This clear, concise presentation nicely answers most questions, leaving listeners both educated and entertained.--Teresa Bateman, Brigadoon Elementary School, Federal Way, WA (c) Copyright 2010. Library Journals LLC, a wholly owned subsidiary of Media Source, Inc. No redistribution permitted. All rights reserved.

(Intermediate) In Comets, Stars, the Moon, and Mars (rev. 5/07), Douglas Florian succinctly describes what happened to Pluto in 2006: ""One day it got fired."" But how did this heavenly body get the job in the first place? And why the scientific pink slip? Scott connects these two questions with the certainty that future discussions will change, because scientific knowledge is not static. The first two chapters cover historical discoveries that led to the identification and naming of each planet. Scott then turns her attention to the way scientists think, making clear the differences between scientific hypotheses, theories, and laws. The fourth chapter outlines Pluto's planetary peculiarities and leads to the process of defining a planet -- a definition that leaves Pluto out in the cold. Assuming that this definition will change, Scott offers no speculation as to the nature of that change and no hypothesis that she believes will be proven. Instead, she reiterates the powerful assertion that we don't know what we will know in the future. Illustrations include photographs of astronomers and outer space; artists' renderings of simulations, such as a protoplanetary disk forming around a star; and diagrams of various planetary features. A glossary, recommended readings and websites, and an index round out the book. (c) Copyright 2010. The Horn Book, Inc., a wholly owned subsidiary of Media Source, Inc. No redistribution permitted. All rights reserved.

Joining the rush of revised views of the solar system for young readers that has been following in the wake of the International Astronomical Union's decision to redefine Pluto (and some other fellow wanderers) as "dwarf planets" rather than the full-fledged sort, this production shows several signs of haste, from a narrative that fails to note that Pluto has more than one moon to a chapter that opens with a full page, uncaptioned photo of a vague smear of light. Scott launches into a clear, simply phrased but standard and mostly off-topic history of astronomy and the discovery of our solar system. Aside from that blur, the accompanying space photos, diagrams, artists' conceptions and art reproductions are up to this author's and publisher's usual high quality, but as more focused, considered treatments of the topic are already available or likely to be coming soon, don't rush to buy this one. (index, reading list) (Nonfiction. 9-11) Copyright ©Kirkus Reviews, used with permission.

Scott takes the 2006 downgrading of Pluto from planet to dwarf planet as a teachable moment for discussing questions such as how the number of planets has changed through the centuries, what can be called a planet, and how scientists come to conclusions—and occasionally change their minds. Following a section on early astronomy, a succinct, timely, and somewhat surprising account of planetary history begins with Herschel's 1781 discovery of the seventh planet, Uranus. Twenty years later, Piazzi found Ceres, which was considered the eighth planet. In 1846, Galle discovered Neptune, bringing the total to nine. When objects similar to Ceres were found in the same orbit, all (including Ceres) were placed in a new category: asteroids. In other words, even before the discovery of Pluto, there were once nine planets, but one of them was demoted. Beautifully designed, the book includes many well-captioned, color illustrations, from period portraits to NASA images to artist's conceptions. A glossary and lists of recommended books and Web sites are appended. A good choice for updating astronomy collections. Copyright 2007 Booklist Reviews.

Gr 3–6— Many people were shocked at Pluto's demotion from a planet to a dwarf planet. How could it be a planet one day, and then not a planet the next? This exceptional book (Clarion, 2007) by Elaine Scott explains exactly why the change took place. She leads readers through a brief history of astronomy, starting with the ancient Greeks and moving up to Ptolemy, Copernicus, Galileo, Kepler, Newton, and modern astronomers. As she aptly points out, our views of the universe have changed many times as our knowledge base has expanded, and future changes are inevitable. The scientific process is presented, and the thinking behind the new definitions is carefully explained, as are the definitions themselves. In this recorded version of the book, Pete Larkin reads Scott's informative text with a rich voice. "Space Fact" boxes, as well as the glossary, are read by a female voice to give them distinction. This clear, concise presentation nicely answers most questions, leaving listeners both educated and entertained.—Teresa Bateman, Brigadoon Elementary School, Federal Way, WA

Gr 3–6— It's been a year since Pluto was reclassified as a "dwarf planet." In the meantime, library print collections have had a void in the 523.4 section. This handsome volume will fill that space neatly. Through engaging and child-friendly language, Scott discusses the history and science behind the discovery of the nine planets. Terms are defined, scientists are introduced, and a time line of planetary milestones is included. Kepler and Newton are two of the scientists whose work is explained in the context of space exploration. By the last chapter, with the details of Pluto's discovery, size, and structure, and the definitions provided by a committee of the International Astronomical Union in place, the change in Pluto's status comes as no surprise. Groundwork is laid for future discoveries and further revisions in terminology in the ever-developing science of astronomy. Beautifully designed from cover to cover and including numerous captioned color photos and other illustrations from a variety of sources, this book entices browsers to look closely. Serious readers will find plenty of detail and well-chosen references for further research. A great resource.—Carol S. Surges, McKinley Elementary School, Wauwatosa, WI