In UFOlogy, a close encounter is an event in which a person witnesses an Unidentified Flying Object. This terminology and the system of classification behind it was started by astronomer and UFO researcher J.Allen Hynek, and was first suggested in his 1972 book The UFO Experience: A Scientific Inquiry. He introduced the first three kinds of encounters; more sub-types of close encounters were later added by others, but these additional categories are not universally accepted by UFO researchers, mainly because they depart from the scientific rigor that Hynek aimed to bring to ufology.
Close Encounter of the First Kind (CE-I):-
A UFO sighting at close range without tangible evidence.
Close Encounter of the Second Kind (CE-II):-
Same as the first but with tangible physical evidence, like-
Radar returns, Photos, damage to area, crop circles, animal disturbances etc etc
Close encounter of the Third Kind (CE-III):-
Same as the first two but also interactions or sightings off UFOnauts.
NB:- however this does not include Conactee encounters.
Close Encounter of the Fourth Kind (CE-IV):-
Used for cases of Abductions of a human beingAbductions of a human being.
Close Encounter of the Fifth Kind (CE-V):-
Used to denote encounters that are joint, bilateral contact events produced through the conscious, voluntary and proactive human-initiated or cooperative communication. Known more commonly as Contactees.
The UFO researcher Ted Bloecher proposed six subtypes for the close encounters of the third kind in the Hynek's scale.
A: An entity is observed only inside the UFO
B: An entity is observed inside and outside the UFO
C: An entity is observed near to a UFO, but not going in or out.
D: An entity is observed. No UFOs are seen by the observer, but UFO activity has been reported in the area at about the same time
E: An entity is observed. But no UFOs are seen and no UFO activity has been reported in the area at that time
F: No entity or UFOs are observed, but the subject experiences some kind of "intelligent communication"