Unidentified phenomena in space, in the Earth's atmosphere, and in waters are too important to leave their exploration to the military and scientific laypersons. Their proper scientific study is important for a variety of reasons; in particular, scientists and the public at large need to know the basic facts, to be informed about the way evidence is recorded, and to understand the difference been reliable evidence and fiction, as well as between plausible explanations and fantasy.With this objective, the book surveys the history of UFO observations, the variety of recorded phenomena, and recounts the efforts of investigative commissions and their published findings.Although wild rumors are demystified in the process, this is not an exercise in rumor-bashing. An open and at the same time critical mindset is the key.