Roswell is often considered the most infamous UFO incident of all time, but reports of unidentified flying objects certainly didn’t begin (or end) there. For thousands of years, people have described seeing strange flying structures of light, clouds, even fire. But as our cultural fascination grew with extraterrestrial life in the 20th century, so did the number of UFO sightings. As Josh Gates and the Expedition Unknown: Hunt for Extraterrestrials crew embark on their exploration of Roswell and other UFO incidents by talking to researchers, historians and eyewitnesses around the world, we’ll look back on some of the other most famous reported UFO sightings in history.

The Rendlesham Forest Incident

Sometimes referred to as “Britain’s Roswell,” the U.K.’s most well-known UFO sightings were reported in late 1980 on a Royal Air Force military base near England’s east coast. On Dec. 26 of that year, the first sighting occurred when two United States Air Force members reported seeing lights falling to Earth over nearby Rendlesham Forest at around 3 a.m. According to an official Air Force memo that later documented the incident, the servicemen entered the forest to investigate and saw a metallic object giving off lights and moving around. When local police arrived, they reportedly didn’t see any lights other than the bright beacon of a nearby lighthouse, but later discovered markings near the site.

A few days later, more servicemen went to investigate the forest site and reported seeing three bright lights in the sky that shone for hours. Astronomers and researchers have disputed the sightings as bright stars and the site markings as indentations made by animals, while the lieutenant who wrote the memo and a few witnesses maintain what they reported in December 1980. 

PS: Hear more from eyewitness and base commander at the time Lt. Col. Charles Halt when Josh Gates visits Rendlesham Forest on Expedition Unknown: Hunt for Extraterrestrials. 

Battle of Los Angeles

According to a reference book published by the National UFO Reporting Center, California tops the list of states with the most reported UFO sightings, with the highest number of incidents occurring in Los Angeles between 2001 and 2015.

One of the most notable first sightings in the Sunshine State happened in February 1942, during World War II, which involved an unusual military attack. The attack on Pearl Harbor had happened only three months before, and on the night of Feb. 24, military units on the California coast were instructed to prepare for Japanese raids. On the morning of Feb. 25, an unidentified aircraft was spotted on the radar 120 miles west of Los Angeles and disappeared.

From there, air raid sirens were raised, a citywide blackout was instated, bright anti-aircraft searchlights punctured the night sky and a mass defense air raid was launched. Reports of unidentified flying objects, foreign aircrafts and even airplane crash landings came pouring into local police departments. The mass chaos led to the deaths of at least five civilians from heart attacks and car accidents during the citywide blackout and vast property damage from shrapnel.

Later, it was discovered that the unidentified object was not from an enemy combatant. Several contradictory reports from witnesses, the government and newspapers at the time stated seeing balloons, aircraft, hovering objects and other phenomena in the night sky, which added to the confusion and wartime paranoia.

The 1952 Washington, D.C. UFO Incident

Like many prominent UFO reports, it started with an unusual and unexpected aircraft on military radars. On July 19, 1952, air traffic controllers at Ronald Reagan National Airport detected movement on their radars from aircraft that weren’t scheduled to arrive in the area, and strangely, apparently moved with sudden speeds that couldn’t be detected by the radar screens.

The following weekend, eyewitness accounts from area citizens, airline crew members and military personnel reported seeing flashes of light zooming in the sky, and other unusual occurrences. To calm national anxiety and slow the reports of UFO sightings that were interfering with emergency calls, the Air Force held the largest press conference since World War II at the time to address the odd activity, which they attributed to stars, meteors and meteorological phenomena such as temperature inversion, causing energy that could be detected by radars.

The Belgian UFO Wave

The longest-lasting series of reported UFO sightings in Belgium began in November 1989 and ended the following April. Around 13,500 people claimed to witness seeing large, triangular flying objects hovering low in the sky. In the spring of 1990, military fighter pilots investigated and pursued some of the unidentifiable objects, but the objects flew out of range before the pilots could observe anything further. It was written off as a harmless mystery and remains one of the largest alleged UFO sightings in history.

The 'Flying Saucers'

The phrase “flying saucer” has been associated with descriptions of UFO sightings for seemingly forever. But the term was actually coined by the press after a sighting was reported by pilot Kenneth Arnold in 1947, the same year as the Roswell incident.

While traveling to Yakima, Wash., for a business trip, Arnold noticed bright light reflecting off the side of his plane. To his surprise, he said he spotted nine aircrafts flying in a “V” formation towards Mount Rainier at around 1,700 miles per hour. He described the movement as “a saucer if you skip it over water,” which was misinterpreted by newspapers to mean the objects were shaped like saucers, thus coining the term. Over the following weeks, multiple UFO sightings were reported, followed by the largest incident in Roswell.

The four-part special event Expedition Unknown: Hunt for Extraterrestrials premieres Oct. 4 at 9|8c on Travel Channel.