CORROBORATED
CF-GEI-20120408241 CORROBORATED

The Mauguio Moon Illusion Case

CASE FILE — CF-GEI-20120408241 — CASEFILES CLASSIFIED ARCHIVE
Date Date when the incident was reported or occurred
2012-04-27
Location Reported location of the sighting or event
Carnon Plage, Mauguio, Hérault, France
Duration Estimated duration of the observed phenomenon
40 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
1
Country Country where the incident took place
FR
AI Confidence AI-generated credibility score based on source reliability, detail consistency, and corroboration
85%
On April 27, 2012, at 00:20 hours, a single witness observed a yellow luminous phenomenon over the étangs (lagoons) of Grec and Pérols at Carnon Plage, near Mauguio in southern France. The witness described the object as crescent-shaped, appearing nearly stationary before performing back-and-forth movements in the western sky. The observation lasted approximately 40 minutes, during which no sound was detected. The witness provided a sketch indicating the phenomenon's direction at an azimuth of approximately 290 degrees. GEIPAN (France's official UFO investigation service under CNES) conducted a thorough investigation including analysis of the witness sketch, video footage, astronomical charts, and meteorological data. The investigation revealed that the observed direction precisely matched the Moon's position in the western sky that night. Video analysis confirmed the object was indeed the Moon, occasionally obscured by passing clouds. The apparent back-and-forth movements reported by the witness were determined to be an optical illusion caused by the eastward movement of cloud cover, creating the false perception that the Moon was moving westward against the clouds. Meteorological records corroborated the presence and eastward movement of clouds during the observation period. No other witnesses came forward to report the phenomenon, and GEIPAN classified this case as "A" - fully explained with certainty.
02 Timeline of Events
2012-04-27 00:20
Initial Observation
Witness begins observing yellow crescent-shaped luminous phenomenon over the étangs du Grec and de Pérols at azimuth 290° (western sky)
00:20-01:00
Perceived Anomalous Movement
Witness observes apparent back-and-forth movements of the object. Object appears nearly stationary between movement episodes. No sound detected throughout observation.
During observation
Video Recording
Witness records video footage of the phenomenon, which later proves instrumental in identification. Video captures Moon being intermittently obscured by clouds.
01:00
Observation Ends
Witness concludes 40-minute observation period. No other witnesses report the phenomenon to authorities.
Post-incident
GEIPAN Investigation
Official investigation analyzes witness sketch, video footage, astronomical charts showing Moon position at azimuth 290°, and meteorological data confirming eastward cloud movement
Post-investigation
Classification A Assigned
GEIPAN conclusively identifies object as the Moon with apparent movement caused by optical illusion from eastward-moving clouds. Case closed with highest certainty rating.
03 Key Witnesses
Anonymous Witness 1
Civilian observer
medium
Single witness who observed phenomenon from Carnon Plage area near the lagoons. Provided detailed sketch and video recording of the observation.
"Le phénomène lumineux jaune est en forme de croissant de Lune quasi statique avant des déplacements en va et vient."
04 Analyst Notes -- AI Processed
This case represents a textbook example of misidentification caused by the autokinetic effect and relative motion illusion. The witness's credibility is not in question; rather, this demonstrates how even careful observers can be deceived by well-understood optical phenomena. Several factors support the explained classification: (1) the crescent shape matches the Moon's phase on that date, (2) the azimuth of 290° precisely corresponds to the Moon's position, (3) the yellow color is consistent with lunar observation near the horizon, (4) video evidence definitively shows the Moon being obscured by clouds, and (5) meteorological data confirms eastward cloud movement that would create the perceived westward motion. The 40-minute observation duration actually strengthens the explanation rather than casting doubt on it. The witness remained focused on the phenomenon long enough to record video, which became instrumental in solving the case. The absence of additional witnesses is unremarkable given the late hour (past midnight) and the mundane nature of the actual stimulus. GEIPAN's classification system rates this as 'A' - the highest level of certainty for explained cases, indicating zero ambiguity in the identification.
05 Theory Comparison
BELIEVER ANALYSIS
SKEPTIC ANALYSIS
Confirmation Through Multiple Data Sources
Skeptical analysis confirms the official explanation through convergent evidence: astronomical software shows the Moon at exactly the reported position and phase; meteorological records prove cloud movement in the direction that would create the perceived illusion; video footage eliminates any ambiguity by showing the Moon itself; and the absence of additional witnesses is expected for a misidentification of a common celestial object. No anomalous characteristics remain unexplained.
06 Verdict
ANALYST VERDICT
This case is conclusively explained as a misidentification of the Moon enhanced by an optical illusion. The convergence of witness testimony, astronomical data, video evidence, and meteorological records leaves no room for alternative explanations. While the witness genuinely perceived anomalous movement, this was entirely the result of relative motion between the Moon and moving clouds - a well-documented perceptual phenomenon. The case serves educational value in demonstrating how atmospheric conditions and cognitive biases can transform ordinary celestial objects into seemingly mysterious phenomena. The thorough GEIPAN investigation methodology, combining multiple data sources, exemplifies best practices in UFO case resolution. Confidence level: 100%.
AI CONFIDENCE SCORE:
85%
07 Community Discussion
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