World UFO Day is an awareness day for people to gather together and watch the skies for unidentified flying objects.
 The day is celebrated by some on June 24, and others on July 2.
 June 24 is the date that aviator Kenneth Arnold reported what is generally considered to be the first widely reported unidentified flying object sighting in the United States, while July 2 commemorates the supposed UFO crash in the 1947 Roswell UFO Incident.
Edward J. Ruppelt (July 17, 1923 – September 15, 1960) was a United States Air Force officer probably best known for his involvement in Project Blue Book, a formal governmental study of unidentified flying objects.
 He is generally credited with coining the term "unidentified flying object", to replace the terms "flying saucer" and "flying disk" - which had become widely known - because the military thought them to be "misleading when applied to objects of every conceivable shape and performance.
 For this reason the military prefers the more general, if less colorful, name: unidentified flying objects.
 UFO (pronounced Yoo-foe) for short."
68–86 Bar and Restaurant, also known as Bar 86, is an upmarket bar and restaurant located at 68–86 Cromwell Road, Kensington, London, near the Natural History Museum.
 It is located in a white stucco building, part of the Radisson Edwardian Vanderbilt Hotel.
 The restaurant serves British cuisine with "Pacific Rim" influences.
 The interior has been described as having "wooden floors and unusual objects of art".
 Catherine Middleton spent her hen night at the bar before her wedding to Prince William.
Douglas Campbell (June 7, 1896 – December 16, 1990) was an American aviator and World War I flying ace.
 He was the first American aviator flying in an American-trained air unit to achieve the status of ace.
James Willett Moseley (August 4, 1931 – November 16, 2012) was an American observer, author, and commentator on the subject of unidentified flying objects (UFOs).
 Over his nearly sixty-year career, he exposed UFO hoaxes and he engineered hoaxes of his own.
 He was best known as the publisher of the UFO newsletters "Saucer News" and its successor "Saucer Smear", which became the longest continuously published UFO journal in the world.
The Kenneth Arnold UFO sighting occurred on June 24, 1947, when private pilot Kenneth Arnold claimed that he saw a string of nine, shiny unidentified flying objects flying past Mount Rainier at speeds that Arnold estimated at a minimum of 1,200 miles an hour (1,932 km/hr).
 This was the first post-War sighting in the United States that garnered nationwide news coverage and is credited with being the first of the modern era of UFO sightings, including numerous reported sightings over the next two to three weeks.
 Arnold's description of the objects also led to the press quickly coining the terms "flying saucer" and "flying disc" as popular descriptive terms for UFOs.
UFO sightings in outer space are sightings of unidentified flying objects reported by astronauts while in space that they could not explain at the time.
 These sightings have been claimed as evidence for alien visits by ufologists, although prosaic explanations have since been found for almost all of them.
 Some of the alleged sightings never occurred: science fiction writer Otto Binder perpetuated a hoax claiming Apollo 11 Commander Neil Armstrong had encountered UFOs during the Apollo mission.
 UFO proponents see comments by astronauts or photos processed by NASA as one of the "strongest bodies of evidence" because they are considered to be of high trustworthiness; however, NASA Assistant Administrator for Legislative Affairs, Robert F. Allnut, concluded in a 1970 letter, "after fifteen years of manned space voyages including space stations and landing on the Moon, spacemen have brought back not a shred of evidence -- verbal, photographic, or otherwise -- for the existence of extraterrestrial spacecraft, or 'UFOs'."
Kenneth A. Arnold (March 29, 1915 – January 16, 1984) was an American aviator and businessman.
 He is best known for making what is generally considered the first widely reported unidentified flying object sighting in the United States, after claiming to have seen nine unusual objects flying in tandem near Mount Rainier, Washington on June 24, 1947.
A professional regurgitator is an entertainer whose act consists of swallowing and regurgitating various unusual objects.
 The objects may consist of anything from live animals (live mice: The Great Waldo), to light bulbs, billiard balls (Stevie Starr) and kerosene (Hadji Ali).
Honda Proving Center of California (HPCC) is a test track established in 1990, and used primarily for testing Honda and Acura automobiles.
 Motorcycles are also tested there.
 HPCC is located near Cantil, California, in Kern County.
 Security is tight, and pilots flying near the track have reported seeing cars immediately heading for cover as they got close to the facility.

Question: World UFO Day is celebrated on the day an American aviator claimed to see nine unusual objects flying near where?
Answer: Mount Rainier, Washington