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Satellite flare (also known as satellite glint) is the phenomenon caused by the reflective surfaces on satellites (such as antennas or solar panels) reflecting sunlight directly onto the Earth below and appearing as a brief, bright "flare".
Iridium satellite flare
The Iridium communication satellites have a peculiar shape with three polished door-sized antennas, 120 degrees apart and at 40 degree angles with the main bus. The forward antenna faces the direction in which the satellite is travelling. Occasionally an antenna will reflect sunlight directly down to the Earth, creating a predictable and quickly moving illuminated spot of about 10 km diameter. To an observer this looks like an extremely bright flare in the sky with a duration of a few seconds.
Ranging up to -8 magnitude (rarely to a brilliant -9.5)1, some of the flares are so bright that they can be seen at daytime; but they are most impressive at night. This flashing has been some annoyance to astronomers, as the flares occasionally disturb observations and can damage sensitive equipment.citation needed
When not flaring, the satellites are often visible crossing the night sky at a typical magnitude of 6, similar to a dim star.
Notes
External links
- Heavens Above allows you to get predictions for when Iridium flares will be seen from your location
- Iridium flares widget for Mac OS X Download free widget to get predictions based on heavens-above.com data
- Iridium flares wigdet for Opera community widget for Opera Browser
- IridiumFlares prediction software (Java application)
- Iridium page at Visual Satellite Observer's Home Page Images and further description of Iridium flares.
