Patrick Moore's latest Guide provides a wry commentary on the history of astronomy: almost all the ideas on Mars based on earth-bound observations turned out to be wrong. Of course there were the scandalous canals. But there were also firm opinions concerning atmospheric pressure (off by a factor of 10), what the polar caps were made of (water, not carbon dioxide), the ""waves of darkening"" that occurred periodically (no such thing). All fell to evidence from the Viking Orbiters and Landers. Typically, Moore launches his survey with minireviews of the solar system, of what causes weather on earth and Mars, of what makes rockets work, and so on. Ever timely, he reminds us we are nearing a new opposition: Earth, Mars, and Sun will be lined up on January 22, 1978 (but the best place for viewing is Australia or South Africa). For the buffs, there are photos, detailed maps, and discussions of surface contours and major features, in addition to reams of statistical information and data from the space shots. Moore echoes other popularizers in giving strong support to continued and collaborative international space exploration as the best route to new knowledge of the solar system. He speculates on the possibility of manned landings, concluding that human life would always have to be maintained in a highly artificial environment. Right now he's all for further exploration of the red planet's unique features: its giant volcanoes, deep valleys, craters, dried-up river beds, and tiny satellites. Good reasoning and good exposition, in the Moore tradition.