Hynek's Taxonomy
UFOlogist J. Allen Hynek had classified UFO sightings into six categories,
three distant ones (nocturnal lights, daylight disks, radar-visual sightings),
and three kinds of close encounters: first, second, and third kind.
Various other UFOlogists have expanded on this list
(Close encounter - Wikipedia),
and I present here that expansion.
- Nocturnal lights
- Daylight disks
- Radar-visual: UFO's seen with both
- Close encounters of the first kind:
close enough to see lots of details
- Close encounters of the second kind:
physical effects
- Close encounters of the third kind:
animated entities ("UFOnauts") visible. Ted Bloecher's subtypes:
- An entity is observed only inside the UFO
- An entity is observed inside and outside the UFO
- An entity is observed near to a UFO, but not going in or out
- 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
- An entity is observed,
but no UFOs are seen and no UFO activity has been reported in the area at that time.
- No entity or UFOs are observed,
but the subject experiences some kind of "intelligent communication"
- Close encounters of the fourth kind:
abduction, often including experiments done by the UFOnauts
- Close encounters of the fifth kind:
cooperative contact and communication with friendly UFOnauts, UFO-contactee cases
- Close encounters of the sixth kind:
human or animal deaths, though this may be an extreme example of the second kind
- Close encounters of the seventh kind: human/UFOnaut hybridization
This taxonomy inspired the name of the movie "Close Encounters of the Third Kind".
A broader taxonomy of extraterrestrial contacts is
The Rio Scale of Extraterrestrial Contacts.
Some of its types include some of these types.
Travels aboard Extraterrestrial Spacecraft
That has not been systematically addressed,
so I have created a taxonomy of various types of control situations.
The spacecraft is
- Under the control of at least some of its human occupants
- Under the control of some extraterrestrials. The human travelers:
- Are traveling by mutual agreement (UFO contactees)
- Are stowaways, present without the authorization of the spacecraft operators
- Are involuntarily present (UFO abductees)
Science-fiction fans should be able to recognize at least some of these scenarios.
I don't know if anyone has written a science-fiction story about
human stowaways aboard an ET spacecraft,
but I once found one about the reverse situation: an ET stowaway aboard a human spacecraft.
Isaac Asimov's "Green Patches" in Nightfall and Other Stories.
But I wouldn't be surprised if there have been numerous SF stories
about versions of the other two ET-spacecraft ones.
Like Jerry Pournelle's Janissaries, which straddles those two possibilities.