Caelum Incognitum
The interactive encyclopedia of ufology
Classifications & scales
- Acronyms to know
- Close encounter of the fifth kind (CE5)
- Close encounter of the first kind (CE1)
- Close encounter of the fourth kind (CE4)
- Close encounter of the second kind (CE2)
- Close encounter of the third kind (CE3)
- Daylight discs (DD)
- FANI (Spanish-language unidentified aerial phenomenon)
- IFO (identified flying object)
- NHI (non-human intelligence)
- Nocturnal lights (NL)
- Observation, report, testimony
- PAN (unidentified aerospace phenomenon)
- Project Blue Book classification
- Radar-visual (RV)
- Strangeness and probability ratings
- UAP (unidentified anomalous phenomena)
- UFO (unidentified flying object)
- USO (unidentified submerged object)
- Vallée classification
Objects & phenomena
- “Saucer nest”
- “Tic Tac”
- Angel hair
- Animal reactions
- Bell-shaped object
- Black triangles
- Boomerang or chevron
- Cattle mutilations
- Cigar-shaped object
- Crop circles
- Diamond or lozenge shape
- Earth lights
- Electromagnetic interference
- Extreme acceleration
- Flying saucer
- Foo fighters
- Ghost lights
- Ghost rockets
- Green fireballs
- Hessdalen lights
- Hovering
- Marfa lights
- Min Min light
- Mothership
- Mystery airships
- Naga fireballs (Mekong)
- Orb
- Physical trace
- Physiological effects
- Ring and luminous crown
- Silent flight
- Spheres
- UFO wave (flap)
- V formation
Encounters, contacts & abductions
- Abduction
- Alien implants
- Allagash abductions (1976)
- Betty Hill’s star map
- Brooklyn Bridge case (1989)
- Contactees
- Hybridization program
- Missing time
- Regression hypnosis
- Screen memory
- Sleep paralysis
- The Andreasson affair (1967)
Reported entities & creatures
- “Little green men”
- “Mantis” or insectoid beings
- Chupacabra
- EBE (extraterrestrial biological entity)
- Flatwoods Monster
- Humanoid
- Men in Black (MIB)
- Mothman
- Pleiadians
- Reptilians
- Roswell “alien autopsy”
- The “Greys”
- The “Nordics”
- Varginha creatures
Explanations & misidentifications
- “Rods” or “skyfish”
- “Unexplained” is not “unexplainable”
- Advertising blimps
- Afterimage
- Aircraft seen head-on
- Anomalous propagation (anaprop)
- Argument from ignorance
- Auroras
- Autokinetic effect
- Ball lightning
- Brocken spectre
- Burden of proof
- Chelyabinsk meteor (2013)
- Children’s testimony
- Colour-changing lights
- Confirmation bias
- Contrails at sunset
- Drones
- False memories
- Falsifiability
- Flares
- Helicopter
- Hoax
- Hole in the clouds (fallstreak hole)
- Hot-air balloons, helium balloons and kites
- Hypnagogic hallucinations
- Insects, birds and dust in the image
- International Space Station
- Iridium flares
- Lens flare and optical reflections
- Lenticular cloud
- Light drone shows
- Light pillars
- Mass hysteria
- Media effect
- Metallised balloons (mylar)
- Meteors and fireballs
- Mirage
- Moon illusion
- Noctilucent clouds and auroras
- Norwegian spiral (2009)
- Occam’s razor
- Pareidolia
- Parhelia and halos
- Pilot sightings
- Plasma
- Project Mogul
- Psychosocial hypothesis
- Radar “angels”
- Reflections in windows
- Reporting bias and base rate
- Sagan standard
- Satellites and Starlink trains
- Searchlights, lasers and aerial advertising
- Size and distance estimation error
- Sky lanterns
- Skyhook balloon
- Skyquakes (booms from the sky)
- Sonic boom
- Space debris reentry
- Sprites and elves
- St. Elmo’s fire
- Stealth aircraft
- Swamp gas
- Temperature inversion
- The Moon, Jupiter, Sirius: astronomical mix-ups
- Tunguska event (1908)
- Twilight launch phenomenon
- Urban legend
- Venus (misidentification)
- Weather or stratospheric balloon
- Will-o’-the-wisp
Hypotheses & theories
- Alcubierre drive
- Ancient astronauts hypothesis
- Anunnaki and Zecharia Sitchin
- Control system (Vallée)
- Cover-up
- Cryptoterrestrial hypothesis
- Disclosure
- Extraterrestrial hypothesis (ETH)
- Ezekiel’s wheel
- Hollow Moon
- Interdimensional hypothesis
- Interstellar distances
- Nibiru (Planet X)
- Secret military technology
- The Dogon and Sirius
- Time-travel hypothesis
- TR-3B
- Trickster phenomenon
- Ultraterrestrial hypothesis
- Vimanas
People
- Aimé Michel (1919-1992)
- Albert Bender
- Antonio Ribera (1920-2001)
- Antônio Vilas-Boas (1934-1992)
- Avi Loeb (born 1962)
- Benjamin Simon (1912-1994)
- Bertrand Méheust
- Betty and Barney Hill
- Budd Hopkins (1931-2011)
- Carl Gustav Jung (1875-1961)
- Carl Hart Jr.
- Carl Sagan (1934-1996)
- Charles Halt
- Christopher Mellon
- Claude Poher
- David Fravor
- David Grusch
- David Jacobs
- Donald Keyhoe (1897-1988)
- Donald Menzel (1901-1976)
- Ed Walters
- Edgar Mitchell
- Edward J. Ruppelt (1923-1960)
- Edward U. Condon (1902-1974)
- Elizabeth Loftus
- Erich von Däniken (born 1935)
- Felix Zigel (1920-1988)
- Fife Symington
- Frank Drake (1930-2022)
- Frank Scully (1892-1964)
- Frederick Valentich (1958-missing)
- George Adamski (1891-1965)
- George Van Tassel
- Gray Barker
- Harold Puthoff
- Harry Reid (1939-2021)
- Hector Quintanilla
- J. Allen Hynek (1910-1986)
- Jacques Vallée (born 1939)
- Jaime Maussan
- James Oberg
- Jean-Jacques Velasco
- Jenny Randles
- Jesse Marcel (1907-1986)
- Jill Tarter (born 1944)
- Jim and Coral Lorenzen
- Jimmy Guieu (1926-2000)
- Jocelyn Bell Burnell
- John E. Mack (1929-2004)
- John Keel (1930-2009)
- Juan José Benítez (born 1946)
- Kenneth Arnold (1915-1984)
- Kevin Randle
- Leonard Stringfield (1920-1994)
- Lonnie Zamora
- Luis Elizondo
- Martin Kottmeyer
- Maurice Masse (1918-2004)
- Michael Persinger (1945-2018)
- Nick Pope
- Paul and Evelyn Trent
- Paul Devereux
- Peter Sturrock (born 1924)
- Philip Corso
- Philip J. Klass (1919-2005)
- Pierre Lagrange
- Raymond Fowler
- Raymond Palmer
- Robert Bigelow (born 1944)
- Robert Hastings
- Robert Sheaffer
- Ryan Graves
- Sean Kirkpatrick
- Seth Shostak
- Stanton Friedman (1934-2019)
- Steven M. Greer
- Susan Clancy
- Ted Phillips
- The Sutton family
- Thomas E. Bullard
- Thomas Mantell (1914-1948)
- Thomas Townsend Brown (1905-1985)
- Timothy Good
- Tom DeLonge (born 1975)
- Travis Walton
- Whitley Strieber (born 1945)
- Wilfried De Brouwer
- Yves Sillard
- Zecharia Sitchin
Organizations & programs
- AARO
- AATIP
- AAWSAP
- Aetherius Society
- AOIMSG
- APRO
- ATIC
- BUFORA
- CEFAA (Chile)
- CISU (Italy)
- CNES
- COMETA report
- Condign Report
- Condon Report
- CSETI and the Disclosure Project
- CUFOS
- Flying Saucer Review
- Galileo Project
- GEIPAN
- GEPAN (1977-1988)
- Majestic 12 (MJ-12)
- MUFON
- NARCAP
- NICAP
- NIDS
- NUFORC
- Project Blue Book
- Project Grudge
- Project Magnet (Canada)
- Project Sign
- Project Twinkle
- Raëlian movement
- Robertson Panel
- Scientific Coalition for UAP Studies (SCU)
- SEPRA
- SIGMA 2 commission (3AF)
- SOBEPS
- Spanish Air Force UFO archives
- To The Stars Academy (TTSA)
- UAPTF
- UK Ministry of Defence UFO desk
Cases, documents & milestones
- “Estimate of the Situation” (1948)
- “GoFast” video (2015)
- “Mummies” presentation at the Mexican Congress (2023)
- 1952 wave
- AAAS symposium (1969)
- AARO historical report (2024)
- Air Force reports on Roswell
- Aurora, Texas (1897)
- Autumn 1973 wave
- Belgian wave (1989-1990)
- Bennewitz affair
- Blue Book by the numbers
- Brookings Report (1960)
- Campeche video (2004)
- Congressional UAP hearing (2022)
- Crash retrieval
- Disclosure Project (2001)
- FBI Hottel memo (1950)
- Gorman dogfight (1948)
- JAL flight 1628 and the FAA
- Jimmy Carter and the 1969 sighting
- July 2023 Congressional hearing
- Kaikoura 1978: the film of the lights
- Kecksburg: the “acorn-shaped” object
- NASA independent study (2023)
- Operation Highjump (1946-1947)
- Operation Prato (Brazil, 1977)
- Philadelphia Experiment
- Phoenix 1997: two separate events
- Project Aquarius
- Project Serpo
- Project Stargate (remote viewing)
- Reagan and the extraterrestrial threat
- Reverse engineering
- Shag Harbour in Canadian archives
- Skinny Bob
- Special Report No. 14
- Tehran 1976 and the DIA report
- The “Battle of Los Angeles” (1942)
- The 1947 wave
- The 1954 French wave
- The 2023 Chinese balloon
- The Cold War context
- The Halt memo (1981)
- The Lubbock Lights (1951)
- The Maury Island incident (1947)
- The New Jersey drones (2024)
- The Pentagon videos (FLIR1, Gimbal, GoFast)
- Timeline of ufology
- Twining memo (1947)
- UAP Disclosure Act
- UAP Disclosure Act (2023)
- UFOs and nuclear sites
- UK UFO files
- US Air Force Regulation 200-2 (1953)
- US Congressional hearings (1966, 1968)
- US intelligence preliminary assessment (2021)
Emblematic places
- Area 51
- Bermuda Triangle
- Bonnybridge (Scotland)
- Cerro Uritorco (Argentina)
- Cydonia (the Mars “face”)
- Devils Tower (Wyoming)
- Dulce Base
- Extraterrestrial Highway
- Giant Rock
- Integratron
- International UFO Museum (Roswell)
- Mount Rainier
- Mount Shasta
- Nazca Lines
- Pine Bush (New York)
- Rendlesham Forest
- Skinwalker Ranch
- The Hudson Valley wave (1982-1986)
- Wright-Patterson (Ohio)
Techniques & investigation methods
- Angular speed and real speed
- ATFLIR
- Azimuth and elevation
- Cognitive interview
- Cross-checking witnesses
- Declassification
- FLIR (infrared imaging)
- FOIA (freedom of information)
- How to describe a sighting
- Image metadata (EXIF)
- Investigation method
- NOTAMs and air traffic
- Parallax
- Photographic analysis
- Reliability of testimony
- Report hotspots
- Sensor artifacts
- Sighting databases
- Sky-checking tools
- Sky-monitoring networks
- Sky-watching equipment
- Special Access Program (SAP)
- The CIA and UFOs
- The five “observables”
- Transponder and ADS-B
- U-2 and A-12
- USS Princeton radar
Culture, media & expressions
- “Fate” magazine
- “Fire in the Sky” (1993)
- “Storm Area 51” (2019)
- Ancient Aliens (2009-)
- Arrival (2016)
- Billy Meier
- Bob Lazar
- Channeling (extraterrestrial mediumship)
- Close Encounters of the Third Kind (1977)
- Coast to Coast AM
- Contact (novel 1985, film 1997)
- Cryptozoology
- CSICOP / Committee for Skeptical Inquiry
- Cuarto Milenio (Spain)
- Doug and Dave
- E.T. the Extra-Terrestrial (1982)
- Exopolitics
- Flying objects in ancient art
- Heaven’s Gate
- Independence Day (1996)
- Paranormal
- Passport to Magonia (1969)
- Pseudoscience and frontier science
- Skeptic, believer, “debunker”
- The 1938 “War of the Worlds”
- The Day the Earth Stood Still (1951)
- The Interrupted Journey (1966)
- The Roswell Incident (1980)
- The Ummo affair
- The X-Files (1993-2002)
- UFO popular imagination
- UFO tourism
- Ufology
- Whistleblower
- World UFO Day
Astronomy, exobiology & SETI
- “Wow!” signal
- 2I/Borisov and 3I/ATLAS
- 3I/ATLAS
- Abiogenesis
- Arecibo message
- Astrobiology
- Biosignature
- Bracewell probe
- Breakthrough Listen
- Breakthrough Starshot
- Dark forest hypothesis
- Drake equation
- Dyson sphere
- Enceladus and Europa
- Exoplanet
- Extremophiles
- Fast radio bursts
- Fermi paradox
- Great Filter
- Habitable zone
- ʻOumuamua
- James Webb Space Telescope
- Kardashev scale
- Kepler and TESS
- Martian meteorite ALH 84001
- Mediocrity principle
- METI (messaging extraterrestrial intelligence)
- Panspermia
- Phosphine on Venus (2020)
- Pioneer plaques
- Project Ozma
- Pulsar CP 1919 (“LGM-1”)
- Rare Earth hypothesis
- SETI
- SETI@home
- Tabby’s Star
- Technosignature
- TRAPPIST-1
- Von Neumann probe
- Voyager Golden Record
- Zeta Reticuli
- Zoo hypothesis