Defined by the Air Force, a UFO is an unidentified flying object, or something that is observed in the sky that cannot be destinguished.  A UFO is either a bright light or a flying saucer.  UFO sightings can be catergorized into "Close Encounters of the First, Second, and Third Kinds"  Encounters of the First Kind are when someone spots a flying saucer in the sky or strange lights.

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The following are two examples of Close Encounters of the First Kind.

In 1947 a pilot, Kenneth Arnold, reported that as he was flying over Mount Rainier in Washington, USA, he spotted nine"flying objects", flying in and out of the Cascade Mountains.  He claimed that they were traveling at speeds of 1,200 miles per hour, more than two times the speed of the fastest airplane of that time.

On December 30, 1978, on an island off New Zealand, bright lights were spotted in the sky, which were filmed.  The "strange lights" in fact were something solid and did appear on radar.  Pilots who were flying above the area also reported that some object flew up beside their planes, and then dashed in front of them and out of sight.

Encounters of the Second Kind are reports of physical evidence of a UFO sightings (burn marks, radioactivity, crop circles, etc.).  The following story is an example of this.

On November 2, 1957, a truck driver was driving down the road in Texas, USA, when he noticed a flame of fire in front of him.  The engine of the car turned off, by itself and the lights went out.  The driver then saw a flying object fly off and when it was out of sight, the lights came back on and he was able to turn the engine on.  The night of this incident, fifteen telephone calls had been made to local police, about UFO sightings.  Other people also claimed that they had engine trouble during that night.

Encounters of the Third Kind are when someone abdmits to have come in contact with a UFO or have gotten of board an alien ship.

On August 19, 1952, in Florida, USA, a man by the name of Desverges was driving with three boys.  They saw a light infront of them, just off the road.  Desverges got out of the car to see what was going on, thinking it was a plane in need of help.  He walked to toward the light and recalled smelling a bad odour, and feeling extremely hot.  He looked up at one point and saw a disc, three to four feet above him.  He heard a sound of a door opening and was covered in a red substance, which made him loose conciousness.  The boys wo had remained in the car, went to get help from the local sheriff.  When they returned to the sight Deverges was walking back toward the car.  He had burn marks on his arms and legs.  There was no lights of flying saucers in the sky and no evidence of anything left behind.  This incident is a Close Encounter of the Second Kind due to the evidence, the burns on the man, and also a Close Encounter of the Third Kind, since the man did actually come in contact with a UFO.

On August 6, 1997 in Mexico City, Mexico, a reporter by the name of Fernando Camacho filmed a UFO.  For twenty- five senconds the UFO remained in the sky above the city.  Reports were also made by witnesses on the ground.  People said they felt "pushed down" by the assumed "gravity beams" UFO's posses.  On woman who was twenty meters below the UFO was burned and her hair fell out a few days after this incident.

........................................  August 6, 1997  Mexico City, Mexico

Close Encounters of the First Kind are the most common and are the most believed (if they really are) due to proof, filmed on video or photographs.  Close Encounters of the Fourth Kind  are reports of people being captured, experimented on and then released by aliens.  Along with the many reports of UFO sightings are fakes of hoaxes.  Many pictures of flying saucers are noticably fake.  Some reports of UFO sightings are also just mistakes.  Many times people mistaken kites, wheather balloons, planets such as Venus and Jupiter, and airplanes for UFO's.  It seems that the shapes of UFO's have changed over the years.

The characteristics of the UFO's that were first sighted in the late 1800's differ from those of today's UFO sightings.  This suggests that as technology improves, the characteristics of UFO' change.  Another factor that changes peoples ideas of what UFO's look like, are movies and television programmes about UFO's and aliens such as The X-Files, Independence Day, and Aliens.  As a result of these films, people put an image into their minds of what a UFO looks like.  Now sightings are altered due to the fact that people expect to see something in a certain way.