1960s: The first and probably most famous claim of alien abduction is reported by Barney and Betty Hill of New Hampshire. The Hills state that on a return trip from Canada in September, their car was followed by a low-flying space ship, and, upon stopping to get a better look at it, they both blacked out, losing two hours of memory. Later, under hypnosis, they tell stories of being taken aboard the space craft and examined by aliens before being set free two hours later.

Today: The U.S. Air Force publishes the "Roswell Report: Case Closed" in an attempt to put an end to rumors that the military tried to cover up a UFO crash in Roswell, New Mexico, in 1947. In the report, the Air Force claims that what witnesses actually saw were remnants of military testing, and Pentagon officials back that claim...