A triangle shape in Seine-Maritime, France

In the night of August 11 to 12, 2012 around 12:25 a.m., a witness looks at the sky and under Cassiopeia he notices an object moving at low altitude toward the west. Coming closer to the roof of the building, the object is more visible and the witness describes it as dark with three ends forming the points of a triangle, luminous circles of a light color, white. The object moves without noise and passes over the roof, no longer allowing the witness to see it. Only one testimony is collected. The white lights, taken individually, clearly suggest Thai lanterns carried by the wind: - the direction of movement indicated by the witness is that of the wind that evening (see the Infoclimat site). - the fact that this happens on a weekend night (in August!) conducive to festive events (lantern releases) supports this hypothesis. - the witness describes a less known feature of these lantern lights: directly below, the light is not full because the underside of the burner is a dark or black disc (see this video) and this matches the description ("The perimeter of these three circles was luminous... while the center was dark, almost as dark as the color of the object." The witness writes that he saw a triangular object but while specifying this: "Dark color barely standing out from that of the night sky. Little contrast between the object and the sky because it was night." He also describes the lights placed at the ends of the triangle "Under the triangular object, a round shape (a circle) was found at each of the three ends (points of the triangle)." This is very likely the classic misidentification (numerous GEIPAN testimonies of triangles and polygons caused by Thai lanterns) known as false shape perception. The eye fills the space between the isolated light points with a usual shape that it believes it sees (Gestalt psychology). Once this mental pattern is in place, this triangle can also be perceived with a certain thickness ("Its edges seemed fairly wide, thick"), simply because the lights of Thai lanterns also have a certain thickness in height (cylindrical objects). Consequently, GEIPAN classifies the case as B: Thai lanterns.