Sighting in Le Verdon-sur-Mer, October 26, 2017

Two witnesses were on a beach when they noticed white filaments drifting down from a clear sky. One of them picked up a few to examine them. The two witnesses then saw two shimmering discs pass quickly and silently, moving side by side across the sky. The filaments kept falling for a few minutes, after which everything returned to normal. The witness managed to keep one filament. To the witnesses, two phenomena had occurred at the same time: filaments, and discs whose speed, shape and colour did not match any known aircraft. They estimated the distance of the discs at 5,000 m for one and 10,000 m for the other.

The investigation settled on spider ballooning, which accounts for most of the features described. In this process, spiders produce silk threads that carry them through the air on the wind. The threads can be rolled into a ball, which could explain the dual appearance of threads and discs seen from the ground. Two apparent objections were set aside. Weather archives showed a wind from the south or west, but the witness described a local south-easterly breeze, consistent with the direction of movement. As for the estimated distances, they are hard to rely on without a point of reference. The account was consistent, the witnesses credible and their observations in agreement.

The case had first been classified B. In mid-September, after the first publication in March 2018, the witness gave GEIPAN a sample of a filament. A CNES laboratory analysed it and found silk fibres mixed with particles, mostly iron oxide. This element, which is close to proof of the hypothesis, allowed the case to be reclassified A: observation of spider ballooning.