Book excerpt: Our knowledge of space has increased spectacularly with the advent of space satellites, telescopes, and probes. Yet, sightings of UFOs continue to be quite high. Clearly, a skilled investigator is needed to discover the unsettling truth behind these alarming objects. This thrilling guide to the extraterrestrial, which includes information about Area 51, crop circles, and Roswell, New Mexico, presents heroic readers with need-to-know scientific knowledge, vocabulary, and experiments they can use to discover the truth about alien life.