- If you saw a flash of light that grew and then faded in about three or four seconds.
- If it was white light as bright as sunlight reflecting off an aircraft.
Then you probably saw an Iridium flare.
This happens when sunlight reflects off the solar panels of one of the Iridium satellites. The reflection is bright enough to be seen in broad daylight. If you want to check whether it was an Iridium flare:
Go to http://www.heavens-above.com/
Select your location from the database
Click on Iridium Flares – Previous 48 hours.