Iridium flares are brief, brilliant flashes of light in the night sky caused by sunlight reflecting off the large, flat antenna panels of Iridium communication satellites[1][3][4]. These satellites, originally launched in the late 1990s to provide global satellite phone coverage, each carried three highly reflective, door-sized antennas arranged around the main body of the spacecraft[1][5][7].
When one of these antennas catches the Sun at just the right angle, it acts like a mirror, directing a concentrated beam of sunlight down to a specific spot on Earth. To an observer on the ground, this appears as a sudden, bright flash—often outshining even Venus, the brightest planet—lasting anywhere from a few seconds up to about 20 seconds[1][3][7]. The flares can reach an apparent magnitude of –8 or brighter, making them visible even in urban areas with significant light pollution and, on rare occasions, even during daylight[1][4][7].
Iridium flares were predictable events, thanks to the satellites’ known orbits and the fixed orientation of their antennas. Enthusiasts could use websites and software to find the exact time and location to view these spectacular flashes[1][5]. However, the original generation of Iridium satellites that produced these flares was deorbited and replaced between 2017 and 2019, and the new satellites do not create the same dramatic flares[4][5].
As you might guess, Iridium flares were responsible for some UFO sightings. The sudden, bright flashes produced by sunlight reflecting off Iridium satellites could easily be mistaken for unexplained aerial phenomena, especially by observers unfamiliar with satellite behavior. These flares were often brighter than any star or planet, appeared unexpectedly, and lasted only a few seconds, making them particularly striking and mysterious to casual skywatchers[12][13].
Astronomers and educators have noted that Iridium flares are a well-known cause of UFO reports, and some have even predicted that future sightings would be attributed to these events as people witness dramatic, unexplained lights in the sky[12]. Online forums and UFO reporting sites include accounts where witnesses later realized they had observed an Iridium flare rather than something truly unidentified[18].
Their predictability and brightness made Iridium flares a common, if unintended, source of confusion for those scanning the night sky, especially before awareness of satellite flares became widespread among the public.
While they lasted, Iridium flares were a favorite among skywatchers and served as a striking demonstration of human-made objects interacting with the cosmos, even sparking discussions about light pollution and the impact of satellite constellations on astronomy[12].
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[1] https://skyandtelescope.org/observing/celestial-objects-to-watch/observing-iridium-flares/
[2] https://www.thoughtco.com/iridium-flares-4148112
[3] https://marysastronomyblogs.blogspot.com/2013/09/what-are-iridium-flares.html
[4] https://en.wikipedia.org/wiki/Satellite_flare
[5] https://flatearth.ws/iridium-flare
[6] https://calgary.rasc.ca/iridium.htm
[7] https://www.satobs.org/iridium.html
[8] https://www.assa.org.au/iridium
[9] https://nuforc.org/sighting/?id=117890
[10] https://www.science.org/content/article/if-alien-ship-left-its-trash-near-earth-here-s-what-it-might-look
[11] https://www.nuforc.org/sighting?id=35935
[12] https://pumas.nasa.gov/examples/determining-altitude-iridium-flares
[13] https://skyandtelescope.org/observing/celestial-objects-to-watch/observing-iridium-flares/
[14] https://en.wikipedia.org/wiki/Identification_studies_of_UFOs
[15] https://www.reddit.com/r/astrophotography/comments/32o0lo/please_help_me_identify_this_for_lack_of_a_better/
[16] https://newspaceeconomy.ca/2025/02/06/are-we-chasing-aliens-or-just-starlink-the-role-of-satellite-flares-in-uap-reports/