J. Allen Hynek spent two decades as the U.S. Air Force's scientific consultant on UFO investigations before publishing this systematic analysis that transformed serious study of the phenomenon. An astronomer at Northwestern University, Hynek began as a skeptic hired to debunk UFO reports but gradually concluded that a small percentage of sightings defied conventional explanation. This book presents his methodology for categorizing encounters--from distant lights to close encounters of the first, second, and third kinds (a classification system later borrowed by Steven Spielberg). Hynek examines hundreds of cases, separating those explainable as misidentified aircraft or atmospheric phenomena from a residue of genuinely puzzling reports by credible observers. He criticizes the Air Force's Project Blue Book for prioritizing public relations over scientific investigation, arguing that ridicule prevented proper study of anomalous data. Hynek does not claim to know what UFOs are; rather, he insists that the phenomenon deserves rigorous scientific attention regardless of its ultimate explanation. The book established the template for subsequent UFO research, distinguishing between sensational claims and careful documentation. Hynek went on to found the Center for UFO Studies and remained the field's most respected scientific voice until his death in 1986. His work demonstrates how genuine curiosity combined with methodological rigor can approach even stigmatized subjects.