Twin Iridium Flares Above Glen Arbor, Michigan

December 31, 2011

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Photographer: Ken Scott; Ken's Website
Summary Author: Ken Scott; Jim Foster

The photo above showing twin iridium flares piercing the night sky was captured above Glen Arbor, Michigan during the evening of September 24, 2011. Iridium flares occur when sunlight is reflected off the solar panels of one of the 66 Iridium satellites that are in orbit around Earth. To correct for changes in the angle these panels make as they orbit, the satellite rotates to reposition the solar cells. It's during this short 10-30 second rotation period that sunlight bounces off the cells towards the Earth's surface. On the ground, the Sun has already set, and the sky may be quite dark. If you're looking at the right spot, you'll notice that the reflection gradually brightens and then may suddenly flare before quickly fading. The brightest flares achieve a magnitude of approximately - 8 or about 85 times brighter than Venus at its brightest. To see when you should be able to see an iridium flare at your location, visit the Heavens Above: Iridium Flares web page.

Photo details: Nikon D300 camera; 3-20 second shots; 800 ISO; 10mm; f/4; tripod used.