Sighting in Sceaux, November 10, 2013

One evening, at around 5 p.m., a witness noticed an intense light that was too bright to look at directly, and it lasted about ten minutes. They were taking photographs of the park at the time. When they looked at the pictures afterwards, they found a streak of light above the horizon, white at first and then red, which they could not explain.

The GEIPAN investigation noted that the phenomenon appeared at sunset, which pointed to a link with the sun. The angle between the sun and the light was about 22°, which is favourable to a sundog (parhelion). This phenomenon requires ice clouds at high altitude: the sky was full of cirrus, and the weather report gave cold, dry conditions. A sundog can also form in aircraft contrails, and both the shape observed and the heavy air traffic made that origin possible. The green spots visible in the photos were internal reflections in the camera optics (lens flare).

GEIPAN classified the case as A: observation of a sundog.