MONETEAU (89) 26.08.2016

On Friday 26 August 2016 at 22:39 in Monéteau (89), a witness and his wife were surprised by 3 orange lights moving silently northwest to southeast through a clear night sky. Their apparent size was compared with a golf ball held at arm's length. They formed a triangle and then passed behind trees. Only 1 account was collected. GEIPAN considers sky lanterns very probable. It notes that releases are frequent on summer evenings, especially weekends, and often appear as a triangle of orange lights. Météociel wind measurements taken 4 km away showed a northerly wind, compatible with an actual or perceived northwest-to-southeast movement at the observation site. The reported sighting was brief, 5 seconds, but the available angular span was necessarily limited to 30° or 40° between the house to the south and tall trees to the north about 10 m away. GEIPAN considers this compatible with lanterns at low altitude, 50 or 100 m, allowing for possible observational errors. The source proposes an overestimate by a factor of 2 or more involving either the actual wind speed, recorded as 6 km/h at the station 4 km away, or the sighting duration; its wording does not make the relationship between those proposed errors fully clear. The witness's main objection was his impression of a solid surface between the 3 lights, supported by his report that stars were obscured as it passed. GEIPAN describes perceptual filling-in between isolated lights at night as common. It also questions whether such a precise observation of hidden stars could be secure during so brief a sighting, noting that the detail was reported later rather than in the initial account, suggesting it had not initially seemed clear or notably unusual. GEIPAN therefore considers sky lanterns a very probable explanation and classifies the case as B: probable observation of sky lanterns.