Sighting in Grenoble, July 3, 2013

At around 10 p.m. on a weekday evening, a witness who was closing their shutters noticed luminous objects crossing the sky in successive waves. The phenomenon lasted about fifteen minutes, and the witness took photographs. The objects were heading south-west. The light, as described and as seen in the pictures, was rather white, similar to the Moon according to the witness.

The investigation found that this direction matched the local wind, based on the weather data consulted. The trajectories repeated from one wave to the next, which supports the idea of objects carried by the wind. Their appearance did not directly suggest Chinese-style sky lanterns, although these are very common, because their light was white. GEIPAN considered instead luminous LED balloons filled with helium, which are now easy to buy. It also noted that twilight alters the perception of colours compared with observation in the dead of night, and that festive balloon releases are less common on a Wednesday than on a Saturday. The case was classified B: probable sighting of luminous helium-filled balloons.