Sighting in Massy, November 4, 2013

Shortly after sunset, a witness noticed an intense, elongated light in the sky, pale with a slight orange tint. It looked like the setting sun reflecting off the body of an aircraft. It lay due west and remained visible for a long time.

The GEIPAN investigation concluded that an orange, luminous shape seen just after sunset strongly suggested a high-altitude object lit by the last rays of the sun. Venus was ruled out: the planet was located further south than the direction the witness gave, and it should have looked round and white, not elongated and orange. The explanation adopted was a distant aircraft contrail, 40 to 80 km away, left by a plane flying at 12,000 m about 50 km from Paris, heading south to north. At that distance such contrails look very small and almost motionless, and they become invisible once the sun drops further below the horizon. The case was classified B: probable sighting of an aircraft contrail.