The debate about UFO's has raged for as long as people have stared into the heavens. Yet to this day the scientific establishment has steadfastly refused to engage in systematic study of what they are. This book examines why. Randles and Warrington establish by detailed case histories of many UFO sightings that unexplained phenomena certainly exist. Picking their way expertly through the maze of misinformation and fantasy, they examine the possible explanations, rejecting the 'standard' view- that UFO's are alien spaceships- in favour of more scientifically based and testable ideas. They suggest ways in which scientific standard should be applied and consider the fruits that such enquiries might yield- and the potential consequences for mankind of explaining the hitherto inexplicable.