We've all asked ourselves the question. It's impossible to look up at the stars and NOT think about it: Are we alone in the universe? Books, movies and television shows proliferate that attempt to answer this question and explore it. In OUT THERE Space.com senior writer Dr. Michael Wall treats that question as merely the beginning, touching off a wild ride of exploration into the final frontier. He considers, for instance, the myriad of questions that would arise once we do discover life beyond Earth (an eventuality which, top NASA officials told Wall, is only drawing closer). What would the first aliens we meet look like? Would they be little green men or mere microbes? Would they be found on a planet in our own solar system or orbiting a star far, far away? Would they intend to harm us, and if so, how might they do it? And might they already have visited?

OUT THERE is arranged in a simple question-and-answer format. The answers are delivered in Dr. Wall's...