CORROBORATED
CF-GEI-19800200738 CORROBORATED
The Châteaudun Celestial Misidentification
CASE FILE — CF-GEI-19800200738 — CASEFILES CLASSIFIED ARCHIVE
Date Date when the incident was reported or occurred
1980-02-18
Location Reported location of the sighting or event
Châteaudun, Eure-et-Loir, France
Duration Estimated duration of the observed phenomenon
20 minutes
Object Type Classification of the observed object based on witness descriptions
light
Source Origin database or archive this case was sourced from
geipan
Witnesses Number of known witnesses who reported the event
3
Country Country where the incident took place
FR
AI Confidence AI-generated credibility score based on source reliability, detail consistency, and corroboration
85%
On February 18, 1980, several witnesses in Châteaudun, France, observed what they described as an unusual luminous phenomenon from a residential courtyard. The primary observation involved "une boule lumineuse blanchâtre" (a whitish luminous ball) with a hazy halo, positioned near another object resembling a crescent moon. The witnesses reported the bright sphere remained stationary for several minutes before exhibiting movement "de droite à gauche et de haut en bas" (from right to left and up and down) for approximately twenty minutes. They described the object as appearing three times larger than surrounding celestial bodies and significantly brighter, eventually moving at high speed along a northwest trajectory before gradually disappearing. No sound accompanied the phenomenon.
The observation occurred around 21:00 hours, with gendarmes (French military police) arriving to witness the phenomenon at 21:15. Local press coverage days later referenced the observation of "clair de terre" (earthshine), a phenomenon associated with the new moon that can produce unusual visual effects when combined with atmospheric disturbances. GEIPAN's astronomical analysis confirmed that on this date—two days after the new moon on February 16—only a thin lunar crescent was visible until 21:02, when the Moon set below the horizon. Venus (magnitude -4.19) was positioned directly above the Moon (magnitude -7.70), both low on the horizon.
The official investigation by GEIPAN, France's official UAP research organization under CNES (Centre National d'Études Spatiales), concluded with an 'A' classification—fully explained with certainty. The investigation determined the witnesses observed the Moon displaying earthshine (lumière cendrée) with Venus positioned above it. The perceived rapid movements were attributed to psychological factors including unconscious exaggeration due to horizon proximity and the autokinetic effect, an optical illusion where stationary lights appear to move when stared at intently in darkness.
02 Timeline of Events
~20:45
Initial Observation Begins
Multiple witnesses in Châteaudun observe unusual luminous phenomenon from residential courtyard. They see a whitish luminous sphere with hazy halo near crescent moon-shaped object
~20:50
Stationary Phase
Witnesses observe the luminous ball remaining motionless near the crescent-shaped object for several minutes. Both objects visible low on western horizon
~21:00
Perceived Movement Phase
Witnesses report the bright sphere begins moving from side to side and up and down. This phase lasts approximately 20 minutes. Likely experiencing autokinetic effect
21:02
Lunar Setting
Moon passes below horizon (astronomical fact). Venus remains visible. Witnesses may perceive this as rapid northwest movement of the bright object
21:15
Gendarmes Arrival
French military police arrive and observe Venus still visible low on horizon. Moon has been below horizon for 12-13 minutes. Gendarmes witness Venus before it too sets
21:20-21:30
Venus Setting and Observation End
Venus disappears below horizon. Witnesses interpret gradual fading as object moving away at distance. Silent observation ends. No sound reported throughout
Days later
Local Press Coverage
Local press reports on the observation, referencing 'clair de terre' (earthshine) phenomenon and unusual visual effects from atmospheric disturbances
Investigation
GEIPAN Classification
GEIPAN conducts astronomical analysis using sky charts. Confirms Moon (magnitude -7.70) and Venus (magnitude -4.19) positions. Case classified as 'A' - fully explained
03 Key Witnesses
Anonymous Witness 1
Civilian resident
medium
Primary witness who observed from residential courtyard around 21:00, before moonset
"Une boule lumineuse blanchâtre se tient immobile prés d'un autre objet ressemblant à un croissant de lune... Son volume semble trois fois plus grand que les astres l'environnant et il brille davantage."
Gendarmes (French Military Police)
Law enforcement officers
high
Responded to the initial report and conducted observation at 21:15, approximately 13 minutes after moonset
"Les gendarmes qui ont fait l'observation à 21h 15 ont aperçu Vénus avant qu'elle ne disparaisse elle aussi sous l'horizon, la Lune ayant déjà disparu depuis une douzaine de minutes."
04 Analyst Notes -- AI Processed
This case represents a textbook example of astronomical misidentification compounded by perceptual and psychological factors. The credibility of the witnesses—including French gendarmes who arrived as secondary observers—is not in question; rather, their interpretation of familiar celestial objects under specific conditions led to the misidentification. The timing is particularly instructive: the primary witnesses observed around 21:00 when both the Moon and Venus were visible low on the horizon, while gendarmes at 21:15 only saw Venus, as the Moon had set twelve minutes earlier at 21:02. This timeline perfectly matches astronomical data.
The earthshine phenomenon (clair de terre) is scientifically well-documented and occurs when Earth reflects sunlight onto the dark portion of the Moon during new moon phases, typically visible on evenings 3-5 days after new moon. On February 18, exactly two days post-new moon, conditions were optimal for this phenomenon. The witnesses' description of a "hazy halo" around the luminous object aligns with atmospheric refraction effects near the horizon. The reported "rapid movements" are almost certainly attributable to the autokinetic effect—a well-studied perceptual illusion where sustained fixation on a point light source in darkness creates the impression of erratic movement. This effect is amplified near the horizon where atmospheric turbulence can cause actual twinkling and minor positional shifts.
05 Theory Comparison
BELIEVER ANALYSIS
SKEPTIC ANALYSIS
Perceptual Illusion Amplified by Expectation
The witnesses' report of dramatic movements and unusual size are classic symptoms of perceptual errors when observing bright celestial objects near the horizon. The autokinetic effect is well-documented in aviation psychology and has caused numerous UFO reports. When observers fixate on a bright point source (Venus) against a dark sky with minimal reference points, the brain interprets normal eye movements and atmospheric shimmer as object movement. The witnesses' unconscious exaggeration of movement speed, likely influenced by the unusual appearance of earthshine on the Moon and local UFO interest suggested by press coverage, transformed a mundane astronomical configuration into a seemingly anomalous event. The complete absence of corroborating reports from other locations despite the claimed brightness and duration further supports misidentification rather than any anomalous phenomenon.
06 Verdict
ANALYST VERDICT
This case is definitively explained as a misidentification of the Moon (displaying earthshine) and Venus, both low on the western horizon. GEIPAN's 'A' classification indicates the highest level of certainty in explanation. The astronomical data is irrefutable: sky charts confirm Venus (magnitude -4.19) positioned directly above a thin lunar crescent (magnitude -7.70), visible until 21:02 on February 18, 1980. The witnesses' sincere report of unusual movement patterns does not indicate deception but rather demonstrates how even trained observers (gendarmes) can misinterpret celestial objects under specific conditions. The combination of earthshine creating an unusually bright lunar appearance, atmospheric distortion near the horizon, psychological expectation following a reported UFO sighting, and the autokinetic effect fully accounts for all reported observations. This case has minimal significance for UAP research but serves as an excellent educational example of how natural phenomena can be misperceived.
AI CONFIDENCE SCORE:
85%
07 Community Discussion
VIEW ALL >// NO COMMENTS YET
Be the first field agent to contribute analysis on this case.
08 Live Chat 1 ROOM
ENTER LIVE CHAT
Real-time discussion with other field agents analyzing this case.