Planets--A Smithsonian Guide
by Thomas R. Watters
Macmillan, New York, 1995, 256 pp.
Black and white and color photographs and illustrations. Hardcover. $24.95.

Planets and Their Moons--National Audubon Society Pocket Guide
by Gary Mechler, Steven K. Croft, Melinda Hutson, and Robert Marcialis
Alfred A. Knopf, New York, 1995, 192 pp.
Color photographs and black and white illustrations. Softcover. $7.99

Despite all our efforts in the scientific community to make planetary exploration as exciting as a xeroxed viewgraph, the general public still thinks it’s neat to look at and learn about the other planets in our solar system. There is a need for and a market available to those who can condense, explain, and showcase for the public the spectacular images that have been returned from over 30 years of manned and unmanned planetary exploration. Perhaps the most notable of past efforts at this is The New Solar System, which was edited by two popular science writers but had each chapter written by a scientific expert (in some cases a loose definition of the term “expert” is required). While it is an excellent book, The New Solar System is seven years out of date, and consequently lacks images and the resulting scientific discoveries from the Magellan, Galileo, Clementine, and Hubble missions. Here I review two up-to-date publications, both produced by organizations that excel at bringing science to the people. One of my interests in these books (and perhaps yours as well) is their potential use as a full-color supplement to planetary science textbooks, most of which are sparsely illustrated and all of which have only black-and- white images.

The first of these, Planets, is written by Tom Watters of the Air and Space Museum as part of a series of Smithsonian Guides. This book uses the format of a planetary science textbook, but its writing style and depth of presentation is intended for a popular audience. The book begins with an overview of the history of planetary exploration and a short summary of planetary formation theory. He then starts with the Sun and moves outward, describing some of the interesting features of each of the solar system bodies and discussing some of the science along the way. For example, for Saturn he begins with a history of exploration, then discusses Saturn’s interior structure, follows with the composition, origin, and behavior of the rings, and concludes with brief descriptions and explanations of the geology of each of Saturn’s larger moons. Interspersed among the object-by-object descriptions are a variety of feature articles describing such topics as cratering, individual NASA missions, phases of the Moon, etc. The last chapter, “Comparing the Planets,” is perhaps the most interesting. It compares the distances, sizes, and interior structures of the planets along with surface features like craters and volcanos. Following the last chapter is a glossary, shaded relief maps of the terrestrial planets, comparison tables, and an index. The book is lavishly illustrated, both with spectacular images and color three-dimensional schematic diagrams.

While I was impressed with the book and thought it was quite good, it is not without its faults. Many of the images are noticeably false-colored with no identification of such. Someone at the Air and Space Museum must like the color green, because a lot of generally gray bodies end up green-tinted in the book. I know this isn’t some bizarre error in the printing process because plenty of grayscale images come out gray in the book. It’s not uncommon for images of the same body on the same page to be printed with completely different color schemes. There are also some examples of what I’d call sloppy writing. In some cases things are stated incorrectly:  A description of how a radar altimeter works is given for how radar imagery is collected; poor wording and poor definitions of the terms “lithosphere” and “crust” make the discussion of terrestrial mantle convection and plate tectonics incomprehensible; the wrong (much smaller) crater is identified as Odysseus on Tethys, making the comparison with Hershel on Mimas quite confusing. In other cases the effort to simplify, in my opinion, reduces clarity and introduces incorrect concepts: Although the difference between mass and weight is defined in the glossary, throughout the text a person’s weight on other planets is given in both pounds and kilograms; a map shows earthquake locations around the world without noting that these must be earthquakes above some magnitude and after a particular date; planetary distances in one case are given in terms of the travel time for a plane traveling at the speed of sound, but it is not noted that the speed of sound is a variable dependent on the properties of the material the sound is traveling through. These may seem like minor points, but the need for accurate and precise writing is greatest for books written for a popular audience, because while a scientist can recognize what the author really means by a poorly written statement, the general public will simply be left confused. The instances of sloppy writing are not numerous, but occur often enough that I wonder whether a thorough final review was performed at the galley-proof stage of publication. I hope the Air and Space Museum will tidy up these loose ends before the next print run, because overall Planets is a pretty good book.

The second book, Planets and Their Moons, an Audubon Society product and one of their Pocket Guide series, takes a very different approach to presenting the fruits of planetary exploration. There is a brief introduction that talks about solar system formation, similarities and differences of the planets, and planetary motions. Most of the remainder of the book is devoted to 4" × 6" images (the size of the book) of planetary bodies with an extended figure caption on the facing page. They begin with a couple of planetary comparison images, then work outward from Mercury to Pluto, and finish with comet images. In my opinion, this is the best collection of planetary images ever put into a single book. It is a masterful combination of telescopic images and NASA press release photos. The figure captions are clear and concise, putting each photograph in perspective, identifying important features, giving scales where appropriate, and explaining any unusual color schemes. While not written in textbook style, a great deal of planetary science is contained within the figure captions, and someone who reads the book cover to cover will come away with a pretty good understanding of the field. The flow of photographs is logical and well done. For example, Mercury images begin with telescopic images of a half- Mercury and a transit of the Sun, then move to a Mariner 10 mosaic of a half hemisphere, and finish with closeups of Discovery Scarp and Caloris Basin. The book closes with directions and tables for observing the planets, and then a very sparse index. While there are a few images of the Moon, there are none of the Sun: These two bodies are covered in great detail in another Pocket Guide entitled The Sun and the Moon. Whenever I have taught a solar system course I have always wished the students had a high-quality set of images to refer to, and Planets and Their Moons fits the bill perfectly. Its cost is low enough that I can make it a required supplement to the textbook I use in the course.

In summary, both these books represent high-quality, up-to-date, well-illustrated presentations of planetary science to the general public.

--Robert Herrick

(Dr. Herrick is a research scientist at LPI.)


The Space Telescope Science Institute (STScI) and the Astronomical Society of the Pacific (ASP) have announced the availability of RealSky CD, the digitized Palomar Observatory Sky Survey, compressed by a factor of 100, on eight CD-ROMs. For the first time, amateur astronomers, educators, and the public have access to the actual sky survey plates used for more than 30 years by research astronomers. The unprecedented level of telescopic detail, especially of extended images like galaxies, clusters, and nebulae, is not available in any other astronomical software package.

The images are digitizations of the E plates from the first NGS-POSS, conducted with the Oschin Telescope (48" Schmidt) on Palomar Mountain during the 1950s. The NGS-POSS was funded by a grant from the National Geographic Society to the California Institute of Technology. With funding from NASA, the more than 750 plate images were first digitized during an intensive 8-year effort by STScI astronomers to prepare the Guide Star Catalog that provides the coordinates of target stars used by the Hubble Space Telescope to acquire and lock onto celestial targets.

RealSky CD is a more compressed version of the original Digitized Sky Survey (DSS), which was made available on 102 CD-ROMs two years ago. The DSS was compressed by a factor of 10 and offered images that were nearly indistinguishable from the original data. The compression factor of RealSky is not suitable for professional research but provides an invaluable tool for the educational and amateur communities. RealSky CD offers single-color (one passband) images of the entire northern sky, down to -15 declination--the approximate location of Sirius--and angular resolution of 1.7 seconds, revealing stars as faint as 19th magnitude.

The RealSkyView software included with the CDs allows users to view and manipulate the images under Windows (3.1, ’95, NT) or Macintosh operating systems. UNIX and VMS software is also included with both versions. Both RealSky CD and the original 10× Digitized Sky Survey can be accessed directly from TheSky (v.4) astronomy software by simply clicking on the desired sky area and specifying image size. CDs are packaged with instruction manual and accompanying software.

The eight CD-ROM set costs $250.00. Within the U.S., add $16 for shipping and handling charges; Canada and Mexico residents add $20; all other countries add $50 for delivery by airmail. California residents please add applicable sales tax. Use your Visa or Mastercard to order at 1-800-335-2624 or send orders by check, credit card, or institutional purchase orders to The Astronomical Society of the Pacific, RealSky CD Orders, 390 Ashton Avenue, San Francisco CA 94112. USA. Phone: 415-337-1100; fax: 415- 337-5205. E-mail:


The Lunar Geotechnical Institute announces a new technical report, “Trafficability of Lunar Microrovers (Part 3),” TR96-01, available free on request from LGI, P.O. Box 5056, Lakeland FL 33807-5056. Phone/fax:  941-646-1842.