CORROBORATED
CF-GEI-19790500629 CORROBORATED

The Gentilly Moon-Jupiter Conjunction Sighting

CASE FILE — CF-GEI-19790500629 — CASEFILES CLASSIFIED ARCHIVE
Date Date when the incident was reported or occurred
1979-05-31
Location Reported location of the sighting or event
Gentilly, Val-de-Marne, France
Duration Estimated duration of the observed phenomenon
several 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
2
Country Country where the incident took place
FR
AI Confidence AI-generated credibility score based on source reliability, detail consistency, and corroboration
85%
On May 31, 1979, at 00:40 (12:40 AM), two witnesses in Gentilly, a southern suburb of Paris in the Val-de-Marne department, observed unusual luminous phenomena in the western sky. The primary object was described as voluminous, crescent-shaped, and orange in color, visible for several minutes. A secondary object also appeared briefly during the observation period. The witnesses were observing due west from their location. GEIPAN (France's official UFO investigation service under CNES) conducted a thorough astronomical analysis of the sighting. Their investigation revealed that the reported observation time and direction corresponded precisely with a notable astronomical configuration. The sky chart for that morning showed Jupiter at magnitude -1.49, the star Pollux at magnitude 0.98, and most significantly, the Moon setting at magnitude -9.51, all positioned due west as reported by the witnesses. The case received GEIPAN's highest confidence classification of 'A' (explained with certainty), concluding that the witnesses had observed an astronomical conjunction of celestial bodies. The crescent-shaped orange object was identified as the setting Moon, with Jupiter and Pollux providing the additional luminous points. This represents a textbook example of how unfamiliarity with astronomical phenomena can lead to UFO reports, even when the explanation is straightforward and verifiable.
02 Timeline of Events
1979-05-31 00:40
Initial Observation
Two witnesses in Gentilly observe a voluminous, crescent-shaped orange object in the western sky
00:40 + moments
Secondary Object Appears
A second luminous object becomes visible to the witnesses for a brief period
00:40 + several minutes
Observation Concludes
Witnesses complete their observation after watching the phenomena for several minutes
Post-incident
Official Report Filed
Witnesses report the sighting to GEIPAN for investigation
Investigation phase
Astronomical Analysis Conducted
GEIPAN analyzes sky charts and confirms presence of Moon (mag -9.51), Jupiter (mag -1.49), and Pollux (mag 0.98) in western sky at reported time
Final determination
Case Classified 'A' - Explained
GEIPAN determines witnesses observed astronomical conjunction of setting Moon with Jupiter and Pollux
03 Key Witnesses
Anonymous Witness 1
civilian
medium
One of two witnesses who observed and reported the phenomenon from Gentilly. Provided accurate directional and temporal information.
Anonymous Witness 2
civilian
medium
Second witness who corroborated the observation of the luminous phenomena in the western sky.
04 Analyst Notes -- AI Processed
This case demonstrates excellent investigative methodology by GEIPAN. The agency cross-referenced the witness report with precise astronomical data, including magnitude calculations for celestial bodies visible at the exact time and location. The crescent moon setting in the west would indeed appear orange due to atmospheric scattering (Rayleigh scattering), particularly when near the horizon. Jupiter, being the second-brightest object in the night sky after Venus, would have been exceptionally prominent at magnitude -1.49. The witness credibility appears moderate to high, as they accurately reported the direction (due west), timing (00:40), and general appearance of what they saw. Their description of a 'voluminous crescent-shaped orange object' is perfectly consistent with a setting crescent moon. The secondary object likely refers to Jupiter, though Pollux could also have been noticed. The witnesses made the responsible decision to report what they considered unusual, and their observations were precise enough to allow for definitive astronomical verification. This case serves as an excellent calibration example for distinguishing between genuine anomalous phenomena and misidentified natural astronomical events.
05 Theory Comparison
BELIEVER ANALYSIS
SKEPTIC ANALYSIS
Misidentification of Common Celestial Phenomena
The witnesses, likely unfamiliar with lunar phases and planetary positions, misinterpreted a perfectly ordinary astronomical event as something anomalous. The setting crescent moon can appear dramatically orange or red when near the horizon due to increased atmospheric path length. Combined with bright Jupiter, this created a visually striking but entirely natural scene that prompted the UFO report.
06 Verdict
ANALYST VERDICT
This case is definitively explained with complete confidence. The witnesses observed the setting Moon in conjunction with Jupiter and the star Pollux. Every detail of their report—timing, direction, appearance, and duration—matches the astronomical record perfectly. GEIPAN's 'A' classification is entirely justified. While this case holds no mystery, it has educational value in demonstrating how even experienced observers can misinterpret celestial phenomena when conditions create an unfamiliar appearance. The orange coloration of the moon near the horizon, combined with its crescent phase and the presence of bright Jupiter, created a visually striking scene that the witnesses understandably found noteworthy. This case exemplifies the importance of astronomical verification in UFO investigations and serves as a reminder that many sightings have prosaic explanations that can be confirmed through scientific analysis.
AI CONFIDENCE SCORE:
85%
07 Community Discussion
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