UFO phenomena can be roughly divided into four categories: misunderstanding of known natural phenomena, unknown natural phenomena and unknown natural creatures. The fourth category refers to high-performance aircraft with obvious intelligent flight capability that are not disclosed by the Air Force, that is, some experimental disk aircraft that are not disclosed by the Air Force. It can be seen that UFOs and alien UFOs cannot be equated.
Since the 1940s, a glowing flying saucer has been found over the United States. At that time, newspapers called it an "oval luminous body", which was the beginning of contemporary people's interest in UFOs. Later, people focused on UFO reports around the world, but so far no evidence widely accepted by the scientific community has been found to prove that they came from extraterrestrial civilization.
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Characteristics of UFOs:
First, you can hover in the air, or move in an instant, or suddenly stop at high speed. Against physics. There are also some UFOs that sway zigzag in the air, flying in a completely irregular way, but they can disappear without knowing it.
Second, most UFOs photographed by witnesses have no engine sound and are almost silent.
Third, there is no tail gas emission.
4. Multiple witnesses means that personal illusion can be ruled out, and the filmed film can be confirmed to be completely error-free.
Fifth, super magnetic field. In most UFO sighting videos abroad, when UFOs appear, animals such as cats and dogs nearby will behave abnormally, such as dogs barking in the direction of UFOs, frogs dodging, cockroaches flying out of windows and so on.
References:
Baidu encyclopedia -ufo