Rating: 
Summary: Concise, useful starting point.
Review: The biggest advantage to his book is that it concisely draws together the general facts about stars, planets, and atmospheres that one needs to design the physicality of worlds for hard-science fiction. Though not all encompassing or exhaustive of the subject, there's enough data to enable one to make choices for a world and then research those choices to the depth necessary to meet one's needs without having to become an expert in astrophysics and/or biochemistry.
Rating: 
Summary: Good even for non-aspiring SF writers
Review: This is a book about the science for, rather than the science of, science fiction. This should perhaps be viewed as supplemental to material on the actual construction of science fiction stories. The focus in particular is on geology, astronomy and planetary dynamics so that the reader will know what details can be ascribed to a planet and remain believable. You will get both qualitative overviews of various topics with more quantitative insertions which one can use to facilitate back-of-the envelope calculations for constructing worlds. These insertions may be skipped over without interfering with the flow of the book and is probably better that you do so even if one has a strong mathematical background (one can always go back later with a calculator to do some constructions). Due to my background in physics, I found myself familiar with most of the material presented in the first two-thirds of the book. However, I still enjoyed it as it was presented in a concise, logical manner. A variety of topics are covered, including: * The relationship between large moons and rotational stability of a planet
* The relationship between planetary dynamics and climate
* Possible unusual configurations of moons, planets and stars
* The role and dynamic range of greenhouse gasses
* The role plate tectonics plays in a livable planet
* Possible alternate forms of life
I did however find the last 10% of the book to have escaped my interest. The author began to divulge into more bizarre scenarios which were hard to relate to.
Rating:
Summary: An excellent and imaginative reference
Review: This is a superb guide to world building, firmly grounded in physics yet pushing the envelope of imagination. It contains a number of fascinating ideas which I'm sure will add richness to my SF writing, and at the same time provides lots of useful equations for working out the details. The chapter on planets which might bear life "not as we know it" is the most fascinating, though far too short. However, my one complaint is about that chapter. Gillett is repeatedly too quick to assume that the absence of fire and uncorroded metals would trap an alien race in the Stone Age forever. An imaginative writer could surely think of other routes to technology. Overall, though, a splendid book and an invaluable resource for the hard-SF writer.
Rating:
Summary: Excellent, but superficial
Review: This is an excellent reference, writen in a clear, conversational style. I won' repeat the similar comments made by the other reviewers. My only complaint: it doesn't go into much detail. I realize that Dr. Gillett had to write a book anyone could use for their sci-fi, be they engineer or English major. He couldn't go math-crazy. Well, as an engineer, I would have liked to see a chapter or two, added at the end, intended for people who aren't scared of differential equations and who want to BUILD a world, not just outline it. My experience, in both industry and graduate school, is that the obscure implications you encounter while modeling a system can be as interesting and important as the final answer you achieve. Dr. Gillett just gives us the final answer. So, to sum up: EXCELLENT book and REQUIRED reading. But, they should have thrown in another chapter of MATH.
Rating:
Summary: Excellent, but superficial
Review: This is an excellent reference, writen in a clear, conversational style. I won' repeat the similar comments made by the other reviewers. My only complaint: it doesn't go into much detail. I realize that Dr. Gillett had to write a book anyone could use for their sci-fi, be they engineer or English major. He couldn't go math-crazy. Well, as an engineer, I would have liked to see a chapter or two, added at the end, intended for people who aren't scared of differential equations and who want to BUILD a world, not just outline it. My experience, in both industry and graduate school, is that the obscure implications you encounter while modeling a system can be as interesting and important as the final answer you achieve. Dr. Gillett just gives us the final answer. So, to sum up: EXCELLENT book and REQUIRED reading. But, they should have thrown in another chapter of MATH.
Rating:
Summary: Unique in its beauty
Review: This is probably the best and only book that clearly states the current understanding of stars and formation/evolution of planets around them, in plain speech. The information is as extensive as it is scientifically accurate which is a great plus for an aspiring fiction writer who does not want to look over the countless pages of an Encyclopaedia Formulae on astrophysics. Besides the numerous formulas one needs to create a (scientifically) cohesive world, Gillett also gives many tidbits from the fiction writing over the course of time, allowing you to become familiar with the possibilities of several future technologies/discoveries. Also included are several studies of fictuous odd-ball worlds ( one is an ocean world filled with sulfuric acid). This book will likely be useful to the writer as well as the explorer within everyone.
Rating:
Summary: Great resource!
Review: World-building is the book everyone is looking for without knowing it until they've found it. Clear and concise (if sometimes a tiny bit dry), Gillett is a user-friendly guide for the novice in creating believable new worlds. Setting influences everything about a story, and good settings can generate so many ideas for stories -- it's great to have a resource that helps you get it right!
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