Iridium flare

An Iridium flare or satellite flare is a flash of light in the sky caused by sunlight reflected off an artificial satellite. More precisely, the term "Iridium flare" refers specifically to a flare produced by the first Iridium series of communication satellites, whose large, reflective, panel-like antennae caused very bright, predictable flares.

When they occurred, they could be the brightest things in the night sky and, because of the speed at which satellites orbit, could appear to move very quickly. The flares were short-lived, as the satellite's solar orientation and angle relative observers on the ground changed fast with the satellite's orbital motion and the rotation of the Earth. As a result of their unique appearance and general ignorance about Iridium flares, Iridium flares were one of the phenomena most commonly mistaken for UFOs and little green men, second only to and refracted light from celestial bodies.

In the late 2010s, Iridium Communications replaced its original communication satellites with a new series called Iridium NEXT. These provide higher bandwidth, but have a different design that does not produce the iconic flares. Most of the original satellites were deorbited, and Iridium flares have become correspondingly extremely uncommon. Similar flashes are, however, still produced by some other satellites.