Wednesday, August 8, 2012

The Satellite Flares

There is this phenomenon that occurs very frequently, and which could easily be mistaken to something totally different.
i am talking about Satellite Flares (AKA Iridium Flares). this astronomical phenomenon is attributed to some of the man made space objects including a constellation of more than 65 satellites called Iridium Satellites and the International Space Station (ISS) etc.
when one of these satellites travel on a path viewable by an observer on the Earth, and the observer is in the shadow while the satellite is in the sunlight, the satellite appears to glow like a star or even brighter than a star most of the time.
An Iridium Satellite has two antennas which are about the size of a door and due to its tilted angle the sunlight is reflected to the Earth below on a surface that measures approximately 10km in diameter. and when the observer stands in this region while the satellite passes by, it appears to glow brightly for a few seconds. but in order for it to be visible, the observer must be in the shadow (means after sunset or before sunrise) and the satellite must be in the sunlight. occasionally there are flares bright enough to be seen while the sun is still above the horizon.
Iridium Flares can be as bright as magnitude -9 (the smaller the number, the brighter. for comparison, Venus at its brightest is about magnitude -4.7 and the full moon is about magnitude -12 and the sun magnitude -26, the brightest star in the night sky, Sirius, is -1.47. each number is 2.5 times brighter than the previous number, for example 2 is 2.5 times brighter than 3, and -3 is 2.5 times brighter than -2)
i have seen a flare way before 1997 (the time Iridium Satellites were sent to orbit), and it was almost the size of the full moon when it was brightest and lasted about 30 seconds. now the question is what did i see? i think it would remain a mystery.
To check the timings of Iridium Flares in your area, please go to and choose your location and click the link for that purpose.