What is a flying saucer?

 What is a flying saucer? The term was coined by a U.S. Air Force press officer for the Roswell UFO incident in 1947 (referring to a "saucer-shaped" object), and it quickly caught on as an evocative synonym for UFOs (unidentified flying objects). The term has since migrated to mean any unexplained airborne object of great interest to the public.

But the first English use of flying saucer dates back only about a decade before Roswell, and the word actually refers to a small, spherical model made by a well-known toy maker of hard-rubber balls in 1870. The word flying saucer was first used in an article about it that appeared in the New York Sun on May 3, 1870. At least three other notable publications (the Scientific American, Harper's Weekly and Frank Leslie's) also published pieces on or references to flying saucers in 1869-70.

Why do people believe in flying saucers? There are various beliefs about UFOs, such as they're extraterrestrial spacecraft or that they're military aircraft that have been perfectly disguised to hide their true nature from the public. Some people believe there's a simple explanation for UFOs: natural phenomena, hoaxes, airplanes, balloons, and so on. Nevertheless, there are many different explanations for what UFOs might be.

How many flying saucers have been reported? Reported sightings of UFOs may number in the hundreds of thousands. A dedicated agency within the United Nations has recorded over 300,000 such sightings from around the world since 1947; about 70% of these have been determined to be hoaxes, delusions or misidentifications.

Is there any hard evidence that flying saucers exist? No physical evidence has ever been found by anyone who claims to have had a close encounter. Have flying saucers ever been photographed? Photographic evidence of UFOs is ambiguous. Some photos show unusual shapes which could be interpreted as unexplainable phenomena, but the objects do not correspond to any known aircraft and thus cannot be accepted as proof of UFOs. However, some "sightings" have been corroborated by radar observations or photographs.

What are popular theories about flying saucers? The extraterrestrial hypothesis: UFOs are spacecraft from another civilization, usually presumed to be from another planet but possibly from a different dimension or time. [And no, the Greys aren't ETs.] The military hypothesis: UFOs are advanced aircraft developed by some nations (or others) and hidden in secret programs. [Likewise, ETs are not a military secret.] 

The government-industrial complex hypothesis: UFOs are extraterrestrial spacecraft or aircraft developed by the U.S. government for use in espionage and reconnaissance (e.g., as part of the ongoing project Blue Book) but "disappeared" at some point in the past. [I'd say that about 99% of modern UFO sightings are due to misidentifications of natural or man-made phenomena!] 

The psychological hypothesis: UFOs are naturally occurring phenomena which cannot be explained by conventional means; this includes hallucinations, illusions and hallucinations created by mental disturbances in people who have had experiences (e.g., abduction by aliens). [That's all fine, but a psychological explanation of UFOs is not inconsistent with another psychological explanation of UFOs — they're hallucinations and delusions created by people with various psychological disturbances.] 

The extraterrestrial hypothesis: UFOs were (or are) actually aliens visiting Earth. [This is a standard version of the religious explanation; in other words, the UFOnauts are otherworldly deities or messianic figures who will save us from the old world.] The anti-science and anti-rationality hypotheses: UFOs represent an attack by anti-rational forces against science and rationality. [This is actually a weird take on it — hardly anyone claims that alien spacecraft are an attack on science. It's a scientistic way of explaining what people see by resorting to pseudoscientific words such as "alien" and "anti-rational."] 

The occult hypothesis: UFOs are actually a disguised or disguised entities that represent archetypes of the human psyche, such as vampires and demons. [Again, this is hardly a scientific response. This is all fine if you're religious or occultist (and not a physicist or astronomer), but I think it makes the case against UFOs much weaker.

How fast can flying saucers travel? Since UFOs are believed to be able to fly faster than the speed of light, a rough estimate would be thousands or even millions of times faster than the speed of sound – at least several thousand miles per hour.