Satellite flare. View of an Iridium satellite's flare in the night sky over a lake. Satellite flare 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'. With highly reflecting triple antennas, the Iridium communication satellites create the brightest flares in the night sky, some bright enough to illuminate night landscape for a short time. They create predictable and quickly moving illuminated spots of about 10 kilometres in diameter. This flashing has also been a problem for serious deep sky astronomical study, as the flares occasionally disturb observations. When not flaring, the satellites are often visible