The Double Planet is a short science fact book that deals with the Earth-Moon system. Originally written in 1960 and revised in 1966 and 1968, the material contained in this book obviously does not include anything that was discovered as a result of the Apollo landings. To a certain extent, the book was intended to build up interest in exploring the moon, and the cover blurb even makes the somewhat misleading statement that the book contains "fascinating secrets of Man's first step across space - to the moon", even though the book itself does not contain more than a passing reference to the projected human exploration of our closest neighbor.

What the book does contain is a fairly decent introduction to the basic facts of the Earth and the Moon. Starting with the Earth, Asimov discusses how large it is, what it is made of, its orbit, its rotation, and several other physical details concerning our planet. To leaven the dry recitation of facts, Asimov also includes background information concerning how and why we know these things about the Earth, recounting the various creative experiments and painstaking observations made by scientists throughout history that led to the conclusions that are presented in the text. Asimov then moves on to discuss what we know about the Moon (or more accurately, what we knew about it as of 1968), once again interlacing the dry data with background concerning those who discovered the various facts about the Moon and how they went about doing so.

The book is written in Asimov's typically straightforward writing style. As I've noted before, this style can lead to some relatively dry fiction, but works quite well for a science fact piece. The book includes several photos taken by unmanned probes sent to the Moon by NASA, which was probably a decent selling point in the late 1960s, but are fairly mundane now, especially when contrasted with the photos taken by the various Apollo missions that followed. The most interesting element of the book is the timing: written originally just before Gagarin became the first man in space, and revised just one year before the Apollo landings began, the book gives a very readable historical perspective on what we knew about both the Earth and the Moon at the outset of the Space Age. In the decades since we have come to take for granted the vast amount of knowledge that we have gained concerning our universe that has been provided to us by our space endeavors. For that historical perspective alone this book is a decent addition to one's library and despite being more than forty years out of date, it is worth reading.

This review has also been posted to my blog Dreaming About Other Worlds. ( )