Iridium is a satellite constellation consisting of 66 satellites. It provides satellite phone services over the entire Earth surface. The first generation satellites have three door-sized reflective antennas. Because of their reflectivity, Iridium satellites will occasionally reflect sunlight to Earth’s surface. The Iridium flare will look like a bright flash over a few seconds.
Most flat-Earthers deny the existence of satellites. Iridium flares provide an easy opportunity to confirm the existence of satellites, at least until the end of 2018, when they are replaced by newer non-reflecting satellites.
Iridium flares are visible quite often, about 2-4× a night. Sometimes they can be brighter than Venus, and these happen about 3-4× per week. Venus is the brightest object in the sky after the Sun and Moon, so these bright Iridium flares should be easy to see although for only a few seconds.
To observe Iridium flares, we need to know exactly where and when to look. Predictions are provided by astronomic observation websites, like heavens-above.com.
Throughout 2018, older Iridium satellites are being gradually replaced. Old reflecting satellites are being replaced by newer non-reflecting ones. As we approach the end of 2018, Iridium flares will occur less and less often. The final Iridium flare should occur at the end of 2018 or the beginning of 2019.
In the meantime, these are easy opportunities to confirm the existence of satellites and one of the too many ways to prove the flat-Earthers are wrong.