Unidentified flying objects could be so many things, from military aircraft, to tricks of the light, to weather phenomena. But what we really want to know is: are they spaceships carrying visitors from other planets? For hundreds of years, people have been trying to make sense of UFO sightings. Within these pages, readers will discover famous accounts of sightings as well as rational explanations. They'll discover the high-profile figures involved in discussions of alien life and also what it takes to identify a hoax. Tips on what to do when encountering a supposed UFO, and representations of UFOs and aliens in pop culture round out this mysterious and occasionally unsettling text.