An Iridium Flash Sunset . ... Credit Copyright: Jon Teus (Science Society Aranzadi, Spain) Explanation: Did you see that flash? Lasting only about 15 seconds, it's possible that nobody you ask can confirm it, but what you might have seen is sunlight reflecting off an orbiting Iridium satellite. ... Of these, flares from any of the 66 Iridium satellites can be particularly bright, sometimes even approaching the brightness of the Moon. ... NASA Web Site Statements, Warnings, and Disclaimers . ...