The first published book to use the term “UFO” was Donald E. Keyhoe’s 1953 book, Flying Saucers from Outer Space.

The modern UFO era began in 1947 when pilot Kenneth Arnold reported seeing nine disc-shaped objects flying over Mt. Rainer, Washington. A reporter labeled them “flying saucers,” and the term entered mainstream consciousness.

Between 1947 and 1969, 12,618 UFO sightings were reported to Project Blue Book, a UFO research agency that was headquartered at Wright-Patterson Air Force Base. Today, 701 of those sightings remain “unidentified.”

The Bermuda Triangle is an area in the Atlantic Ocean within which unusual events occur. One popular explanation (among many) is that there is a secret undersea UFO base in the area and that there is something about the comings and goings of UFOs that is responsible for the destruction/disappearance of Earth’s ships and planes.

The 1993 movie Fire in the Sky recounts the 1975 abduction of Travis Walton. Before the credits of the movie begin, a title card notes that Walton recently passed a lie detection test about the incident. However, the tests were actually arranged by the studio to generate publicity for the movie’s release. Walton failed or had inconclusive results on lie detector tests administered by authorities.

In the late 1930s, Orson Wells’ radio show The War of the Worlds was so realistic that hundreds of people thought America had really been invaded by aliens and UFOs.

On July 8, 1947, the public information office in Roswell, New Mexico, announced the recovery of a crashed “flying disc” from a ranch near Roswell. The government said it was an experimental balloon that was part of a classified program. However, critics say the government was covering up the discovery of an extraterrestrial spacecraft and its occupants.

In 1948, the U.S. Air force began Project Sign, a UFO investigation agency. Within a year, it was succeeded by Project Grudge which, in 1952, was replaced by the longest-lived of the official inquiries into UFOs, Project Blue Book. From 1952 to 1969, Project Blue Book gathered more than 12,000 reports of UFO sightings or events. About 6% of the 12,000 sightings remain unsolved.

A 1991 Roper poll shows that 4 million people believe they have been abducted by aliens.

The first photographs of a UFO were taken in 1883 by astronomer Jose Bonilla in Zacatecas, Mexico.

The 1961 made-for-TV movie The UFO Incident was one of the first films to show an actual alien rather than just the saucer. The aliens had huge heads with elongated eyes and gray skin.

In the 1960s, popular culture shifted its focus from flying saucers to their pilots. There were more reports of talking to aliens face to face or visiting their usually friendly home worlds. By the 1970s, aliens were more menacing and had turned to crime, such as mutilating cattle, gouging arcane symbols into farmland, and kidnapping humans.

“Foo fighters” and, more rarely “kraut fireballs,” were terms Allied aircraft pilots in WW II used to describe different kinds of UFOs or other mysterious aerial phenomena.

The expression “Oz factor” refers to the sensation of being transported into another reality during a UFO sighting.

On November 23, 1953, First Lieutenant Felix Eugene Moncla, Jr., was sent to intercept an unidentified flying object over Sault Ste. Marie, Michigan. After getting close to the object, Moncla’s plane disappeared from the radar screen and was never found.