Kenneth Arnold UFO sighting
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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.
- 1 Sighting
- 2 Publicity and origins of term "flying saucer"
- 3 Widespread UFO reports after Arnold sighting
- 4 Military investigation of Arnold story
- 5 Skeptical explanations
- 6 Other sightings by Arnold and his opinion
- 7 See also
- 8 References
- 9 External links
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On June 24, 1947, Arnold was flying from Chehalis, Washington to Yakima, Washington in a CallAir A-2 on a business trip. He made a brief detour after learning of a $5,000 reward for the discovery of a U.S. Marine Corps C-46 transport airplane that had crashed near Mt. Rainier. The skies were completely clear and there was a mild wind.
A few minutes before 3:00 p.m. at about 9,200 feet (2,800 m) in altitude and near Mineral, Washington, he gave up his search and started heading eastward towards Yakima. He saw a bright flashing light, similar to sunlight reflecting from a mirror. Afraid he might be dangerously close to another aircraft, Arnold scanned the skies around him, but all he could see was a DC-4 to his left and behind him, about 15 miles (24 km) away.
About 30 seconds after seeing the first flash of light, Arnold saw a series of bright flashes in the distance off to his left, or north of Mt. Rainier, which was then 20 to 25 miles (40 km) away. He thought they might be reflections on his airplane's windows, but a few quick tests (rocking his airplane from side to side, removing his eyeglasses, later rolling down his side window) ruled this out. The reflections came from flying objects. They flew in a long chain, and Arnold for a moment considered they might be a flock of geese, but quickly ruled this out for a number of reasons, including the altitude, bright glint, and obviously very fast speed. He then thought they might be a new type of jet and started looking intently for a tail and was surprised that he couldn't find any.
They quickly approached Rainier and then passed in front, usually appearing dark in profile against the bright white snowfield covering Rainier, but occasionally still giving off bright light flashes as they flipped around erratically. Sometimes he said he could see them on edge, when they seemed so thin and flat they were practically invisible. According to Jerome Clark, Arnold described them as a series of objects with convex shapes, though he later revealed that one object differed by being crescent-shaped. Several years later, Arnold would state he likened their movement to saucers skipping on water, without comparing their actual shapes to saucers, but initial quotes from him do indeed have him comparing the shape to like a "saucer", "disc", "pie pan", or "half moon", or generally convex and thin (discussion below). At one point Arnold said they flew behind a subpeak of Rainier and briefly disappeared. Knowing his position and the position of the (unspecified) subpeak, Arnold placed their distance as they flew past Rainier at about 23 miles (37 km).
Using a dzus cowling fastener as a gauge to compare the nine objects to the distant DC-4, Arnold estimated their angular size as slightly smaller than the DC-4, about the width between the outer engines (about 60 feet). Arnold also said he realized that the objects would have to be quite large to see any details at that distance and later, after comparing notes with a United Airlines crew that had a similar sighting 10 days later (see below), placed the absolute size as larger than a DC-4 airliner (or greater than 100 feet (30 m) in length). Army Air Force analysts would later estimate 140 to 280 feet (85 m), based on analysis of human visual acuity and other sighting details (such as estimated distance).
Arnold said the objects were grouped together, as Ted Bloecher writes, "in a diagonally stepped-down, echelon formation, stretched out over a distance that he later calculated to be five miles". Though moving on a more or less level horizontal plane, Arnold said the objects weaved from side to side ("like the tail of a Chinese kite" as he later stated), darting through the valleys and around the smaller mountain peaks. They would occasionally flip or bank on their edges in unison as they turned or maneuvered causing almost blindingly bright or mirror-like flashes of light. The encounter gave him an "eerie feeling", but Arnold suspected he had seen test flights of a new U.S. military aircraft.
As the objects passed Mt Rainer, Arnold turned his plane southward on a more or less parallel course. It was at this point that he opened his side window and began observing the objects unobstructed by any glass that might have produced reflections. The objects did not disappear and continued to move very rapidly southward, continuously moving forward of his position. Curious about their speed, he began to time their rate of passage: he said they moved from Mt. Rainer to Mount Adams where they faded from view, a distance of about 50 miles (80 km), in one minute and forty-two seconds, according to the clock on his instrument panel. When he later had time to do the calculation, the speed was over 1,700 miles per hour (2,700 km/h). This was about three times faster than any manned aircraft in 1947. Not knowing exactly the distance where the objects faded from view, Arnold conservatively and arbitrarily rounded this down to 1,200 miles (1,900 km) an hour, still faster than any known aircraft, which had yet to break the sound barrier. It was this supersonic speed in addition to the unusual saucer or disk description that seemed to capture people's attention.
Arnold landed in Yakima at about 4.00 p.m., and quickly told friend and airport general manager Al Baxter the amazing story, and before long, the entire airport staff knew of Arnold's claims. He discussed the story with the staff, and later wrote that Baxter didn't believe him.
Arnold flew on to an air show in Pendleton, Oregon, not knowing that somebody in Yakima had phoned in ahead to say that Arnold had seen some strange new aircraft. It was at this time that Arnold studied his maps, determined the distance between Mt. Rainier and Mt. Adams, and calculated the rather astonishing speed. He told a number of pilot friends, and wrote in his account to AAF intelligence that they did not scoff or laugh. Instead they suggested that maybe he had seen guided missiles or something new, though Arnold felt this explanation to be inadequate. He also wrote that some former Army pilots told him that they had been briefed before going into combat "that they might see objects of similar shape and design as I described and assured me that I wasn't dreaming or going crazy." (See Foo fighter.)
Arnold wasn't interviewed by reporters until the next day (June 25) when he went to the office of the East Oregonian in Pendleton. Any skepticism the reporters might have harbored evaporated when they interviewed Arnold at length; as historian Mike Dash records:
- Arnold had the makings of a reliable witness. He was a respected businessman and experienced pilot ... and seemed to be neither exaggerating what he had seen, nor adding sensational details to his report. He also gave the impression of being a careful observer ... These details impressed the newspapermen who interviewed him and lent credibility to his report.
Arnold would soon complain about the effects of the publicity on his life. On June 27 he was reported saying, "I haven't had a moment of peace since I first told the story." He then said a preacher had called and told him that the objects he saw were "harbingers of doomsday" and that the preacher was preparing his congregation "for the end of the world." In another encounter, a woman in a Pendleton cafe noticed him and dashed out shrieking, "There's the man who saw the men from Mars." She ran out "sobbing she would have to do something for the children," Arnold was reported saying "with a shudder".
He then added that, "This whole thing has gotten out of hand. I want to talk to the FBI or someone. Half the people look at me as a combination of Einstein, Flash Gordon and screwball. I wonder what my wife back in Idaho thinks."
Arnold talks of possible non-earthly origins
On July 7, 1947, two stories came out where Arnold again was raising the topic of possible extraterrestrial origins, both as his opinion and those who had written to him. In an Associated Press story, Arnold said he had received quantities of fan mail eager to help solve the mystery, none of it calling him a "screwball". Like the earlier doomsday preacher Arnold spoke of, many of the writers placed a religious interpretation on his sighting. But others, he said, "suggested the discs were visitations from another planet." Arnold added he had purchased a movie camera, which he would now take with him on every flight, hoping to obtain photographic proof of what he had seen.
In the other story, Arnold was interviewed by the Chicago Times:
- "...Kenneth Luis Arnold ...is not so certain that the strange contraptions are made on this planet. Arnold... said he hoped the devices were really the work of the U.S. Army. But he told the TIMES in a phone conversation: 'If our government knows anything about these devices, the people should be told at once. A lot of people out here are very much disturbed. Some think these things may be from another planet. But they aren’t harming anyone and I think it would be the wrong thing to shoot one of them down—even if can be done. Their high speed would completely wreck them…'
- "Arnold, in pointing to the possibility of these discs being from another world, said, regardless of their origin, they apparently were traveling to some reachable destination. Whoever controlled them, he said, obviously wasn’t trying to hurt anyone. …He said discs were making turns so abruptly in rounding peaks that it would have been impossible for human pilots inside to have survived the pressure. So, he too thinks they are controlled from elsewhere, regardless of whether it’s from Mars, Venus, or our own planet."
In an Associated Press story from July 19, Arnold reiterated his belief that if they weren't Army, then they were extraterrestrial:
- "The ex-University of Minnesota swimmer and footballer says he now believes:
- 1. The disks are not from any foreign country.
- 2. The Army could give the answer if it would -- 'if they don't have the explanation now they certainly could do something to find out.'
- 3. If the Army has no explanation the disks must be -- 'and I know this sounds crazy' -- from another planet."
In April 1949, in a skeptical article in the Saturday Evening Post titled "What You Can Believe About Flying Saucers", Arnold was likewise quoted:
- "Since my first observations and report of the so-called 'flying disks' I have spent a great deal of money and time thoroughly investigating the subject... There is no doubt in my mind but what these objects are aircraft of a strange design, and material that is unknown to the civilization of this earth."
The article goes on to say:
- Arnold himself has been conducting a one-man campaign to prove that he did see something out of the ordinary that day over Mount Rainier... Arnold has written other articles for Fate--one titled Phantom Lights Over Nevada, and another Are Space Visitors Here. In the latter, discussing a fisherman's report of seeing weird purplish spheres with portholes maneuvering over the Crown River, in Ontario, Arnold wrote: "Once again, we can be sure that these Canadian blue-green-purple globes are not meteors, nor are they fragments of a comet or Venus. What, then, are they? Spacecraft from another world?"
Clearly Arnold was early leaning heavily towards the Extraterrestrial hypothesis to explain what he and others had seen.
Arnold's sighting was partly corroborated by a prospector named Fred Johnson on Mt. Adams, who wrote AAF intelligence that he saw six of the objects on June 24 at about the same time as Arnold, which he viewed through a small telescope. He said they were "round" and tapered "sharply to a point in the head and in an oval shape." He also noted that the objects seemed to disturb his compass. An evaluation of the witness by AAF intelligence found him to be credible. Ironically, Johnson's report was listed as the first unexplained UFO report in Air Force files, while Arnold's was dismissed as a mirage, yet Johnson seemed to be describing a continuation of the same event as Arnold.
The Portland Oregon Journal reported on July 4 receiving a letter from an L. G. Bernier of Richland, Washington (about 110 miles (180 km) east of Mt. Adams and 140 miles (230 km) southeast of Mt. Rainier). Bernier wrote that he saw three of the strange objects over Richland flying "almost edgewise" toward Mt. Rainier about one half-hour before Arnold. Bernier thought the three were part of a larger formation. He indicated they were traveling at high speed: "I have seen a P-38 appear seemingly on one horizon and then gone to the opposite horizon in no time at all, but these disks certainly were traveling faster than any P-38. [Maximum speed of a P-38 was about 440 miles an hour.] No doubt Mr. Arnold saw them just a few minutes or seconds later, according to their speed." The previous day, Bernier had also spoken to his local newspaper, the Richland Washington Villager, and was among the first witnesses to suggest extraterrestrial origins: "I believe it may be a visitor from another planet." 
About 60 miles (97 km) west-northwest of Richland in Yakima, Washington, a woman named Ethel Wheelhouse likewise reported sighting several flying discs moving at fantastic speeds at around the same time as Arnold's sighting.
When military intelligence began investigating Arnold's sighting in early July (see below), they found yet another witness from the area. A member of the Washington State forest service, who had been on fire watch at a tower in Diamond Gap, about 20 miles (32 km) south of Yakima, reported seeing "flashes" at 3:00 p.m. on the 24th over Mount Rainier (or exactly the same time as Arnold's sighting), that appeared to move in a straight line. Similarly, at 3:00 p.m. Sidney B. Gallagher in Washington state (exact position unspecified) reported seeing nine shiny discs flash by to the north.
A Seattle newspaper also mentioned a woman near Tacoma who said she saw a chain of nine, bright objects flying at high speed near Mt. Rainier. Unfortunately this short news item wasn't precise as to time or date, but indicated it was around the same date as Arnold's sighting.
However, a pilot of a DC-4 some 10 to 15 miles (24 km) north of Arnold en route to Seattle reported seeing nothing unusual. (This was the same DC-4 seen by Arnold and which he used for size comparison.)
Other Seattle area newspapers also reported other sightings of flashing, rapidly moving unknown objects on the same day, but not the same time, as Arnold's sighting. Most of these sightings were over Seattle or west of Seattle in the town of Bremerton, either that morning or at night. Altogether, there were at least 16 other reported UFO sightings the same day as Arnold's in the Washington state area. maptable of Washington state sightings
The flap continues
The primary corroborative sighting, however, occurred ten days later (July 4) when a United Airlines crew over Idaho en route to Seattle also spotted five to nine disk-like objects that paced their plane for 10 to 15 minutes before suddenly disappearing. The next day in Seattle, Arnold met with the pilot, Cpt. Emil J. Smith, and copilot and compared sighting details. The main difference in shape was that the United crew thought the objects appeared rough on top. This was one of the few sightings that Arnold felt was reliable, most of the rest he thought were the public seeing other things and letting their imaginations run wild. Arnold and Cpt. Smith became friends, met again with Army Air Force intelligence officers on July 12 and filed sighting reports, then teamed up again at the end of July in investigating the strange Maury Island incident.
A similar sighting of eight objects also occurred over Tulsa, Oklahoma on July 12, 1947. In this instance, a photo was taken and published in the Tulsa Daily World the following day (photo at right). Interestingly, the photographer, Enlo Gilmore, said that in blowups of the photo, the objects resembled baseball catcher's mitts or flying wings. He was of the opinion that the military had a secret fleet of flying wing airplanes. He had been a gunnery officer in the Navy during the war, and using information from another witness, also a veteran, he performed a triangulation and arrived at an estimation of speed of 1,700 miles per hour (2,700 km/h), or essentially the same estimate as Arnold's. One of the objects, he said, seemed to have a hole in the middle.
Two or three photos of a similar, solitary object were taken by William Rhodes over Phoenix, Arizona on July 7, 1947, and appeared in a local Phoenix newspaper and some other newspapers. The object was rounded in front with a crescent back. These photos also seem to show something resembling a hole in the middle, though Rhodes thought it was a canopy. Rhodes's negatives and prints were later confiscated by the FBI and military. However, the photos show up in later Air Force intelligence reports.
Arnold was soon shown the Rhodes photos when he met with two AAF intelligence officers. He commented, "It was a disk almost identical to the one peculiar flying saucer that had been worrying me since my original observation — the one that looked different from the rest and that I had never mentioned to anyone." As a result, Arnold felt that the Rhodes photos were genuine.
Publicity and origins of term "flying saucer"
Arnold's account was first featured in a few late newspaper editions on June 25, appeared in numerous U.S. and Canadian papers (and some foreign newspapers) on June 26 and thereafter, often on the front page. Without exception, according to Bloecher, the Arnold story was initially related with a serious, even-handed tone. The first reporters to interview Arnold were Nolan Skiff and Bill Bequette of the East Oregonian in Pendleton, Oregon on June 25, and the first story on the Arnold sighting, written by Bequette, appeared in the newspaper the same day.
The term appears
Starting June 26 and June 27, newspapers first began using the terms "flying saucer" and "flying disk" (or "disc") to describe the sighted objects. Thus the Arnold sighting is credited with giving rise to these popular terms. The actual origin of the terms is somewhat controversial and complicated. Jerome Clark cites a 1970 study by Herbert Strentz, who reviewed U.S. newspaper accounts of the Arnold UFO sighting, and concluded that the term was probably due to an editor or headline writer: the body of the early Arnold news stories did not use the term "flying saucer" or "flying disc." However, earlier stories did in fact credit Arnold with using terms such as "saucer", "disk", and "pie-pan" in describing the shape. (see quotations further below)
Years later, Arnold claimed he told Bill Bequette that "they flew erratic, like a saucer if you skip it across the water." Arnold felt that he had been misquoted since the description referred to the objects' motion rather than their shape. Thus Bequette has often been credited with first using "flying saucer" and supposedly misquoting Arnold, but the term does not appear in Bequette's early articles. Instead, his first article of June 25 says only, "He said he sighted nine saucer-like aircraft flying in formation..."
The next day in a much more detailed article, Bequette wrote, "He clung to his story of shiny, flat objects racing over the Cascade mountains with a peculiar weaving motion ‘like the tail of a Chinese kite.' ...He also described the objects as 'saucer-like' and their motion 'like fish flipping in the sun.' ...[Arnold] described the objects as 'flat like a pie-pan and somewhat bat-shaped'." It wasn't until June 28 that Bequette first used the term "flying disc" (but not "flying saucer").
A review of early newspaper stories indicates that immediately after his sighting, Arnold generally described the objects’ shape as thin and flat, rounded in the front but chopped in the back and coming to a point, i.e., more or less saucer- or disk-like. He also specifically used terms like "saucer" or "saucer-like", "disk", and "pie pan" or "pie plate" in describing the shape. The motion he generally described as weaving like the tail of a kite and erratic flipping.
For example, in a surviving recorded radio interview from June 25, Arnold described them as looking "something like a pie plate that was cut in half with a sort of a convex triangle in the rear." His motion descriptions were: "I noticed to the left of me a chain which looked to me like the tail of a Chinese kite, kind of weaving... they seemed to flip and flash in the sun, just like a mirror... they seemed to kind of weave in and out right above the mountaintops..." 
The following day (June 26) were the following quotations attributed to Arnold: 
- United Press: "They were shaped like saucers and were so thin I could barely see them..."
- Associated Press: "He said they were bright, saucer-like objects--he called them 'aircraft'. ...He also described the objects as ‘saucer-like’ and their motion 'like a fish flipping in the sun.’ ...Arnold described the objects as 'flat like a pie pan'."
- Associated Press: "They flew with a peculiar dipping motion, 'like a fish flipping in the sun,' he said. ... He said they appeared to fly almost as if fastened together -- if one dipped, the others did, too."
- Chicago Tribune: "They were silvery and shiny and seemed to be shaped like a pie plate.... I am sure they were separate units because they weaved in flight like the tail of a kite."
On June 27 was the following quotation:
- Portland Oregon Journal: "'They were half-moon shaped, oval in front and convex in the rear. ...There were no bulges or cowlings; they looked like a big flat disk.’ ...Arnold said that the objects weaved 'like the tail of a Chinese kite'."
Two weeks later, Arnold was still referring to the shape of the objects as "saucers" or "saucer-like." In the Portland Oregonian on July 11, he was quoted saying, "I actually saw a type of aircraft slightly longer than it was wide, with a thickness about one twentieth as great as its width. ...I reckoned the saucers were 23 miles away."
Statement to the army
In a written statement to Army Air Forces (AAF) intelligence the following day (July 12), Arnold several times referred to the objects as "saucer-like." At the end of the report he drew a picture of what the objects appeared to look like at their closest approach to Mt. Rainier. He wrote, "They seemed longer than wide, their thickness was about 1/20th their width." (document with Arnold's drawing at right) As to motion, Arnold wrote, "They flew like many times I have observed geese to fly in a rather diagonal chain-like line as if they were linked together. They seemed to hold a definite direction but rather swerved in and out of the high mountain peaks." He also spoke of how they would "flip and flash in the sun." text of written report
A variant object
To complicate the shape descriptions further, a month after his sighting, Arnold was to become involved in the bizarre Maury Island incident. Arnold was dispatched by a magazine publisher to Tacoma to investigate it, although he eventually turned the investigation over to the AAF. In a meeting with two AAF intelligence officers (the same ones who interviewed him on July 12 and for whom he wrote his report), Arnold first revealed one of the nine objects was different, being larger and shaped more like a crescent coming to a point in the back. It was at this time that Arnold was also shown the Rhodes photos of a crescent-shaped object over Phoenix, which Arnold deemed authentic because of the unusual shape.
Some note the object in the drawing bears an uncanny similarity to the WW2 German design, the Horten Ho 229, sometimes further claiming it was captured German technology being tested. But there is no historical evidence of any kind supporting this.
Widespread UFO reports after Arnold sighting
In the weeks that followed Arnold's June 1947 story, at least several hundred reports of similar sightings flooded in from the U.S. and around the world—most of which described saucer-shaped objects. A sighting by a United Airlines crew of another nine disk-like objects over Idaho on July 4 probably garnered more newspaper coverage than Arnold's original sighting, and opened the floodgates of media coverage in the days to follow.
Bloecher collected reports of 853 flying disc sightings that year from 140 newspapers from Canada, Washington D.C, and every U.S. state save Montana. This was more UFO reports for 1947 than most researchers ever suspected. Some of these stories were poorly documented or fragmentary, but Bloecher argued that about 250 of the more detailed reports (such as those made by pilots or scientists, multiple eyewitnesses, or backed by photos) made a persuasive case for a genuine mystery.
Adding intrigue to Arnold's story, the U.S. military denied having any planes at all in the area of Mount Rainier at the time of his sighting. Likewise, on July 6, speculation arose in newspaper articles that the objects being sighted were due to either the "flying wing" or "flying flapjack", a disc-shaped aircraft, both experimental planes under development by the U.S. military at the time (see military flying saucers). The military repeated that neither aircraft could account for the sightings, which is also borne out by historical records.
The most famous UFO event during this period was the Roswell UFO incident, the alleged military recovery of a crashed flying disk, the story of which broke on July 8, 1947. To calm rising public concern, this and other cases were debunked by the military in succeeding days as mistaken sightings of weather balloons. Just before the Roswell story came out, the Army Air Forces in Washington issued a press statement saying they had the matter under investigation and had decided the flying discs definitely were not "secret bacteriological weapons designed by some foreign power", "new-type army rockets", or "space ships".
Military investigation of Arnold story
The first investigation of Arnold's claims came from Lt. Frank Brown and Capt. William Davidson of Hamilton Field in California, who interviewed Arnold on July 12. Arnold also submitted a written report at that time. Regarding the reliability of Arnold's sighting, they concluded:
- "It is the present opinion of the interviewer that Mr. Arnold actually saw what he stated he saw. It is difficult to believe that a man of [his] character and apparent integrity would state that he saw objects and write up a report to the extent that he did if he did not see them."
Despite this, the Army Air Force's formal public conclusion was that Arnold had seen a mirage.
In addition, on July 9 AAF intelligence, with help from the FBI, secretly began an investigation of the best sightings, mostly from pilots and military personnel. Arnold's sighting, as well as that of the United Airline's crew, were included in the list of best sightings. Three weeks later they came to the conclusion that the saucer reports were not imaginary or adequately explained by natural phenomena; something real was flying around. This laid the groundwork for another intelligence estimate in September 1947 by Gen. Nathan Twining, commanding officer of the Air Materiel Command, which likewise concluded the saucers were real and urged a formal investigation by multiple government agencies. This in turn resulted in the formation of Project Sign at the end of 1947, the first publicly acknowledged USAF UFO investigation. Project Sign eventually evolved into Project Grudge, and then the better known Project Blue Book.
- I found that there was a lot of speculation on this report [amongst Sign personnel]. Two factions ... joined up behind two lines of reasoning. One side said that Arnold had seen plain, everyday jet airplanes flying in formation ... The other side didn't buy this idea at all. They based their argument on the fact that Arnold knew where the objects were when he timed them ...
- There was an old theory that maybe Arnold had seen wind whipping snow along the mountain ridges, so I asked Air Force investigators about this. I got a flat "Impossible."
Steuart Campbell has said that the objects Arnold reported could have been mirages of several snow-capped peaks in Cascade Range. Campbell's calculation of the objects' speed determined that they were travelling at roughly the same speed as Arnold's plane, indicating that the objects were in fact stationary. Mirages could have been caused by temperature inversions over several deep valleys in the line of sight.
James Easton was the first of several skeptics to suggest that Arnold may have misidentified pelicans: the birds live in the Washington region, are rather large (wingspans of over three meters are not uncommon), have a pale underside that can reflect light, can fly at rather high altitudes, and can appear to have a somewhat crescent-shaped profile when flying.
In response to skeptical explanations, Bruce Maccabee says a meteor theory would require impossibly slow speeds and durations for brightly glowing meteors on a horizontal trajectory. He says it is impossible for a bird to be as bright as reported by Arnold, and that birds—which could not fly as fast as Arnold's plane—would have steadily moved backward, not forwards, relative to his position.
Donald Menzel's explanations
Donald Menzel was a Harvard astronomer and one of the earliest UFO debunkers. Over the years, he offered several possible explanations for the Arnold's 1947 UFO sighting. Bruce Maccabee disputed Menzel's explanations in a 1986 monograph.
- In 1953, Menzel suggested that Arnold had seen clouds of snow blown from the mountains south of Mt. Rainier. According to Maccabee, such snow clouds have hazy light, not the mirror-like brilliance reported by Arnold. Further, such clouds could not be in the rapid motion reported by Arnold, nor would they account for Arnold first seeing the bright objects north of Rainier.
- In 1963, Menzel proposed that Arnold had seen orographic clouds or wave clouds; Maccabee says that this conflicted with testimony from Arnold and others that the sky was clear, and again can't account for the objects' reported brightness and rapid motion over a very large angular region.
- In 1971, Menzel said that Arnold may have merely seen spots of water on his airplane's windows; Maccabee says that this contradicts Arnold's testimony that he had specifically ruled out water spots or reflections shortly after seeing the nine UFOs. For example, the early Bill Bequette article of June 26 in the East Oregonian has Arnold saying he at first thought that maybe he was seeing reflections off his window, but "he still saw the objects after rolling it down."
Other sightings by Arnold and his opinion
In a 1950 interview with journalist Edward R. Murrow, Arnold reported seeing similar objects on three other occasions, and said other pilots flying in the northwestern U.S. had sighted such objects as many as eight times. The pilots initially felt a duty reporting the objects despite the ridicule, he said, because they thought the U.S. government didn't know what they were. Arnold did not assert that the objects were alien spacecraft, although he did say: "being a natural-born American, if it's not made by our science or our Army Air Forces, I am inclined to believe it's of an extraterrestrial origin." Then he added that he thought everybody should be concerned, but "I don't think it's anything for people to get hysterical about."
The first issue of Fate (1948) featured the article The Truth About The Flying Saucers by Arnold. In 1952 he described his experiences in the book The Coming of the Saucers, which he and a publisher friend named Raymond A. Palmer published themselves.
- Clark, Jerome (1998). The UFO Book: Encyclopedia of the Extraterrestrial. Visible Ink. ISBN 1-57859-029-9.
- Clark, Jerome (2005) . The UFO Encyclopedia: The Phenomenon from the Beginning. A–K. Detroit: Omnigraphics. ISBN 0-7808-0097-4.
- In an interview with CBS Newsman Edward R. Murrow on April 7, 1950, Arnold explained: "In the excitement of it all ... nobody knew just exactly what they were talking about ... They said that I said that they were saucer-like; I said that they flew in a saucer-like fashion", see: Sagan, Carl (March 1997), The Demon-Haunted World: Science As a Candle in the Dark, Ballantine Books, p. 70, ISBN 0-345-40946-9
- The UFO Wave of 1947 by Ted Bloecher, 1967; URL accessed March 7, 2007
- Dash, Mike, Borderlands: The Ultimate Exploration of the Unknown; Woodstock: Overlook Press, 2000; ISBN 0-87951-724-7
- Spokane (Washington) Daily Chronicle, p. 1 , Eugene (Oregon) Register-Guard, June 27, 1947, p. 1 ; Bremerton (Washington) Sun, June 28, 1947, p. 1
- Associated Press story, July 7, 1947, e.g., Salt Lake City Deseret News, p. 3, "Author of 'Discs' Story To Seek Proof" 
- Chicago 'Times', July 7, 1947, p. 3
- Walla Walla (Wash) Union-Bulletin, July 20, 1947, "Man Who Reported 'Flying Saucers' Feels That He Has Been Vindicated"
- Saturday Evening Post, April 30, 1949, p. 129
- Oregon Journal, Portland, July 4, 1947, p. 2
- Michael D. Hall & Wendy A. Connors, Alfred Loedding & the Great Saucer Wave of 1947, online, p. 27
- Hall & Connors, 27
- Hall & Connors, 27-28
- Seattle Daily Times, June 27, 1947, p. 1; Bremerton Sun, June 28, 1947, p. 1
- 5 Discs Sighted by United Flight
- Perhaps the earliest example was the Chicago Sun on June 26, whose headline for the AP story read: "Supersonic Flying Saucers Sighted by Idaho Pilot".
- United Press story from Washington D.C., July 8, 1947, Ted Bloecher, "Report on the UFO Wave of 1947", p. 50 ; Copies of United Press stories
- reprinted in Bloecher, 1967
- Edward J. Ruppelt; Report On Unidentified Flying Objects; New York: Doubleday 1956
- Campbell, Steuart (1994). The UFO Mystery Solved, Chapter 5: The first flying saucers. Explicit Books. ISBN 0-9521512-0-0.
- The Skeptics UFO Newsletter (SUN) #46, July 1997 URL accessed March 13, 2007
- RRRGroup, "Kenneth Arnold and the pelicans" (Wednesday, April 4, 2007); URL accessed June 27, 2007
- Bruce Maccabee, "Another Failed Explanation for the Kenneth Arnold Sighting"
- Maccabee account of Arnold sighting with critique of skeptical explanations
- see Clark, 2005 for more details and Maccabee's website
- The Singular Adventure of Mr Kenneth Arnold
- The Positively True Story of Kenneth Arnold - Part One 10-part series at Saturday Night Uforia
- Out of This World: 60 Years of Flying Saucers by Nigel Watson
- The most complete Arnold sighting description and analysis on the net
- Resolving Arnold part 1
- Resolving Arnold part 2
- Transcript of telephone conversation with Arnold by Edward R. Murrow
- Some early newspaper articles on the Arnold sighting