Sighting in Saint-Denis, December 11, 2016

In the late afternoon, between about 6:30 and 6:45 pm, a driver noticed a red-orange phenomenon in a clear sky. It looked like two streaks topped by a kind of rectangle. At first it seemed motionless, then it rose, gradually faded and finally vanished completely. The sighting lasted three to five minutes. The witness, who was driving, placed it toward the west or southwest. Only one account was collected.

The witness thought it was an atmospheric phenomenon but did not have the knowledge to check. According to GEIPAN, this first impression was probably right: the sighting was most likely clouds lit by the setting sun. Sunset was at 6:45 pm, at an azimuth of 250°, in the direction the witness indicated, and the driver may not have seen the sun beforehand. A few wisps of cloud, strongly lit by the sun, can form orange shapes that are sometimes unusual, and then fade away. Venus and Mercury were also shining in that direction, Venus especially, at 35° elevation. Either the witness did not notice it or it was hidden by a cloud; in both cases, the phenomenon cannot have been seen at 40° elevation as stated, since errors in estimating elevation are very common. GEIPAN therefore classified the case as B: observation of clouds.