Sightings more than 500 feet from the witness are classified as Daylight Discs”, Nocturnal Lights”or Radar/Visual Reports”. Sightings within about 500 feet are subclassified as various close encounters.

A system first suggested by J. Allen Hynek in his 1972 book The UFO Experience: A Scientific Study.

Hynek’s original three levels of close enconter range from the first kind (unexplained odd lights, or non-human aerial objects) to the second (observation of physical evidence) to the third (observation of the occupants).

Later Ufologists suggested encounters of the forth kind (abduction) and the fifth kind (direct communication).

As contact with the alien became increasingly alienating, two more levels were suggested:

Close encounters of the sixth kind involves the death of a human or animal. See also:The Battle of Los Angeles

Close-encounters of the seventh kind involved genetic interchange between aliens and humans. See also:Antonio Villas-Boas