from The Textbook Letter, November-December 1997

Reviewing a science book for high-school honors courses

Astronomy: From the Earth to the Universe
1998. 643 pages + appendices. ISBN: 0-03-024347-5.
Saunders College Publishing, 150 South Independence Mall West,
Philadelphia, Pennsylvania 19106.

A Good, Friendly Textbook by a Lucid Writer

Bing F. Quock

The universe is a pretty broad subject, and writing an up-to-date textbook that tells what astronomers know about the universe is a daunting challenge. Such a book has to include material drawn from physics, biology, meteorology, math and history, among other disciplines.

Astronomy: From the Earth to the Universe is an introductory college text written by Jay M. Pasachoff, who teaches astronomy at Williams College and is the director of the Hopkins Observatory there. With his many years of experience as a professor, Pasachoff is in a good position to know how to teach his subject well and how to make it interesting to students.

I should mention that, some years ago, I used the first edition of Astronomy: From the Earth to the Universe as the textbook for an introductory college course that I taught, and I found it to be excellent. In this review, I am looking at the fifth edition, which is copyrighted in 1998 and is about as up-to-date as a textbook can be, in terms of the information that it provides and the illustrations that it displays. The illustrations include images acquired by the Hubble Space Telescope and even by the Mars Pathfinder spacecraft (1997), as well as a photo of Comet Hale-Bopp (1997).

Pasachoff is a lucid writer and he often adopts a conversational style, as if he were talking directly to the reader. His approach is somewhat gimmicky and includes the use of mnemonic devices, references to popular culture, and other flourishes that engage the reader's attention. In the chapter titled "Our Moon," for example, a light-hearted paragraph is devoted to the famous, bungled line -- "One small step for man, one giant leap for mankind" -- that Neil Armstrong spoke when he became the first man to set foot on the Moon. (Armstrong meant to say "for a man," but he omitted a word and produced a historic utterance that didn't really make sense.) That line has given rise to many spoofs, and Pasachoff notes the one that Bruce McCandless delivered in 1984, when he flew untethered in space: "That may have been one small step for Neil, but it's a heck of a big leap for me." (I am surprised to see, however, that Pasachoff omits a similar quip that Pete Conrad made as he stepped onto the Moon in 1969. Conrad was then the shortest of all the astronauts, and his remark -- offered in a proper lunar setting -- made a better joke.) Pasachoff also quotes the comment that the poet Joseph Brodsky made when he learned that he had won the Nobel Prize for Literature in 1987: "A big step for me, a small one for mankind."

Helping the Reader

The chapters are organized according to the traditional "Earth-out" scheme, starting with Earth-based observations of the sky, then moving outward to the planets, to the stars, and finally to the galaxies. Pasachoff takes the time to explain terms and to give the background information that enables the reader to understand the subject matter. He presents unresolved issues, such as the question of whether Pluto is a planet or a Kuiper body, in a fair manner -- and when he expresses his own opinions, he usually identifies them as such.

Each chapter finishes with a summary of its main points, a list of key words, and some questions, as well as a novel little section called "Correcting Misconceptions." Pasachoff explains this innovation in his preface:

A major new feature in this book is the providing of a set of common misconceptions for each chapter, along with the correct ideas. It has become clear in recent years that students' minds are not blank slates, but that they harbor misconceptions that must be tackled and unlearned before the correct material can be retained.

The end-of-chapter items also include optional exercises based upon RedShift2, a commercial package of astronomy software that is available on CD-ROM.

While Astronomy: From the Earth to the Universe is a reader-friendly book, students will get a surprise if they have expected introductory astronomy to consist entirely of easy, qualitative material and nice pictures. They will encounter some exponential math in the very first chapter ("The Universe: An Overview"), and by the time they get to chapter 23 ("Stars and Their Spectra"), they will have to be ready to deal with stellar physics. For the uninitiated, topics such as electron states, the Stefan-Boltzmann law, and the Hertzsprung-Russell diagram can be intimidating, even when they are presented well. It is possible to teach introductory astronomy without concentrating heavily on mathematical physics, of course, but Pasachoff makes that material available, and the instructor can choose to use it or to skip it. Pasachoff has provided some help here: Throughout the book, he has used asterisks to mark sections of text that are especially easy to omit.

Must high-school students take a course in physics before they take an honors course based on Astronomy: From the Earth to the Universe? Yes, if the teacher plans to cover the entire book: When Pasachoff reaches beyond the solar system to consider astrophysics and cosmology, he addresses many topics that will elude students who have not already had formal instruction in physics, including relativity, as a prerequisite. But if the teacher elects to give a more restricted course that steers clear of highly abstruse topics, then bright students will probably be able to use this book even if they have not completed a physics course.

In its graphic design, Astronomy: From the Earth to the Universe is a typical science textbook of the late 1990s: It has hundreds of boxed sidebars, colorful illustrations, and items printed in the page-margins. For the most part, though, these are not too distracting or intrusive. Many of the illustrations are diagrams, which usually are clear and useful. The few that may confuse more than illuminate include figure 8-7, in the chapter "Our Earth": This diagram is intended to show that "earthquakes occur preferentially at plate boundaries" -- but the plate boundaries themselves aren't shown, so the reader can't actually compare them with the locations of quakes. (This chapter also shows some confused nomenclature. In the caption under figure 8-6, the San Andreas Fault is said to indicate the boundary between the "California" plate and the "Pacific" plate, while figure 8-7 shows an "American" plate and a "Pacific" plate but no "California" plate. It seems to me that Pasachoff's "California" plate and "American" plate are the same object, which is properly called the North American Plate.)

Another image that probably will elicit blank stares from most students is figure 28-20, a 3-dimensional vector graphic representing the detection of a neutrino from Supernova 1987A.

Pasachoff brightens things up by the occasional use of cartoon panels or unconventional photographs, such as the photos of Niels and Margrethe Bohr on a motorcycle (figure 23-10) or of Albert Einstein on a bicycle (figure 30-4). He also uses images of sports stars (such as Tiger Woods or Nancy Kerrigan) and frames from recent movies (such as Jurassic Park and Roxanne), adding captions that relate these images to the topics at hand. Sometimes, though, his efforts to use pop-culture images seem a bit forced. An example is figure 20-16 -- a frame from the George Lucas film The Empire Strikes Back, showing some of the film's characters looking at a galaxy from their spaceship. Pasachoff doesn't say anything about it, and there is no clear reason for its being in the book, though he could have used it as an opportunity to point out that real galaxies do not rotate as quickly as the galaxy depicted in the movie.

Pasachoff has missed some other opportunities by neglecting to show how observations of events taking place on other planets are related to questions about Earth. For example: In chapter 12 ("Mars"), he could have explained how studies of global dust-storms on Mars led to the suggestion that a nuclear war on Earth would engender a "nuclear winter." This would have been all the more interesting because Pasachoff later cites the concept of a "nuclear winter" and tells us that a less severe version of it, the "nuclear autumn" scenario, has been suggested as an explanation for the demise of the ancient dinosaurs; see "The Extinction of the Dinosaurs," a sidebar in the chapter about meteorites and asteroids. (I've always been puzzled about why the combatants in this particular debate seem to feel that the termination of the Age of Dinosaurs must have been due to some single, absolute cause, rather than to a combination of concurrent factors.)

As a whole, however, this latest edition of Astronomy: From the Earth to the Universe is an excellent and timely introduction to the cosmos, appropriate for courses on several levels. I recommend it.

Still, one thing continues to bother me, and I cannot end this review without telling about it. It is a statement in the preface, where Pasachoff declares: "One of my aims in writing this book is to educate voters and prospective voters, showing them that exciting forefront research is going on. One reason for this aim is the hope that they will endorse candidates who will support scientific research in general and astronomical research in particular." That makes me uncomfortable. I know that the American public's appreciation of science is alarmingly poor, and that this can endanger our entire scientific enterprise, but I can't help wondering whether it is wise to say that a major purpose of Astronomy: From the Earth to the Universe is to get people to vote in a particular way. No matter how good Pasachoff's intentions may be, some readers will misinterpret his statement and will be led to see Astronomy: From the Earth to the Universe as a piece of political propaganda. This fine textbook doesn't deserve such a taint, and I wish that Pasachoff had stuck to "aims" that were concerned directly with the teaching of astronomy, which is something that he does very well.

Bing F. Quock is the assistant chairman of the Morrison Planetarium at the California Academy of Sciences, in San Francisco. He specializes in presenting astronomy to the public, and he has principal responsibility for planning and directing the Planetarium's public programs. His scientific interests include comparative planetology.


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