Theoretical background.

 What is now known as the "UFO" is essentially a modern concept born in the second half of the twentieth century. However, there are those who interpret certain passages of the Bible and other traditions originated in ancient cultures, as alleged evidence of ancient UFO sightings. Many argue that, from the distant past, humans tried to adapt what he saw to his intellect, linking the various sightings with known objects near it.

They also note that, if these were unmanned aerial vehicles, there would be equally possible contact with extraterrestrial beings, who conveyed to the various teachings observers. According to this theory, the origin of many past civilizations (Egypt, Babylon, etc...) Lie in these early contacts.

Before he coined the terms flying saucer or UFO, is recorded in a series of strange and in identifications mention aerial phenomena occurred years ago, which would no longer be associated with beliefs, legends and myths, as presumably could have happened in antiquity. These references date from the mid-nineteenth century to the early twentieth century.

Thus, UFO researchers considered the first modern documented sighting, the case in Chile in 1868.3 It was published in the newspaper The Constituent city of Copiapo, and covered the UFO seen in it as a volatile unknown and later that year, as a group of stars or meteors flatness crossing the sky. The phenomenon was observed many times in that area during that year, and is considered by UFO logists as the first surge on record and the beginning of the records as such relate to the UFO issue.

The final phase of sightings is after World War II and in the U.S. began with the sighting that made the businessman Kenneth Arnold on June 24 1947mientras was flying his private plane near Mount Rainier, in Washington.4 reported seeing nine shiny objects with a shape similar to a hang glider or a boomerang, flying on one side of Rainier and heading toward the nearby Mount Adams at incredible speed, estimated that at least 1930 miles per hour, calculating the time taken to travel between two mountains. They marched swiftly as a squadron and moved like a disc makes it bounces off the surface of the water. The newspapers misrepresented the exact words of Arnold and described the objects as saucers.

The ways in which we have seen the UFO phenomenon are varied, and many of them are just reports, so it can be verified, while others are some videos and photos, in which the phenomenon is observed and not detected evidence of forgery and explanation of the phenomenon, so are classified as UFOs.

From the scientific field have asserted that when reports of UFOs are studied in depth, manages most cases be identified with certainty, being that it was fraud, hallucinations, misinterpretations or paridoras of known terrestrial phenomena (comets, phenomena atmospheric satellites, space junk, airplanes, ships terrestrial prototypes, lenticular cloud, etc.) In other cases the phenomenon remains unidentified, so do not pretend that authorizes, for the failure identification achieved with certainty, there is basis for holding that it is alien spaceships. Even in these cases would also be admissible unidentified and logical to assert that involving cases similar to those identified