- Kenneth Arnold: In 1947, Kenneth Arnold reported seeing a series of nine saucer-shaped objects flying near Mount Rainier in Washington state. This sighting is often considered the beginning of the modern UFO phenomenon.
- Roswell: In 1947, a rancher near Roswell, New Mexico, discovered debris from a crashed object. The military initially claimed it was a weather balloon, but later admitted it was a high-altitude surveillance balloon. However, many people believe the debris was from an extraterrestrial spacecraft.
- Project Blue Book: From 1947 to 1969, the United States Air Force conducted Project Blue Book, an official investigation of UFO sightings. Project Blue Book concluded that the vast majority of sightings could be explained by natural phenomena or human-made objects, but a small number of cases remained unexplained.
- Rendlesham Forest: In 1980, several members of the Royal Air Force reported seeing strange lights and objects near Rendlesham Forest in England. The incident is notable because of the high number of witnesses and the fact that the Ministry of Defence initially classified the reports as "top secret."
- Phoenix Lights: In 1997, thousands of people in Arizona and Nevada reported seeing a series of bright, triangular lights in the sky. The lights were never officially explained, and the incident remains one of the most widely reported UFO sightings in history.
These are just a few examples of the many UFO sightings that have been reported over the years. While the vast majority of sightings can be explained by natural phenomena or human-made objects, a small number remain unexplained and continue to fuel speculation about extraterrestrial life.