This book is the fourth rewrite of a classic that I first encountered when I was taking planetary science courses at the University of Colorado. It never occurred to me that I'd be editing the fourth edition, along with Beatty and Chaikin. It was a very rigorous process, made all the more so by the exacting standards we set up for ourselves in terms of getting the best experts in the field to write for us, and to apply our own editorial standards to the work. The result is a book that people continue to use, even if some of the science is a wee bit out of date. It remains a very general reference guide to solar system objects.
People often ask if there's a fifth edition coming out. The answer right now is, "no". I'd love to work on a revision and new edition, and such discussions have been held. But, so far, it remains a "work for the future". In the meantime this 4th Edition is easily found on the secondary market, and deserves a place on the reference bookshelf.