Okay... Maybe I'm a nerd, but Saturday I saw my first Iridium flare (mag. -8 for you supernerds!) and all I can say is "holy s*** that was cool!" I can't believe how bright it was.
Iridium satellites have an unusual historical aspect to them, but the bottom line is that there are something like 80 of these satelites slowly spinning in a very precise and consistent orbit that allows for their loctation to predicted. Near sunset and sunrise these satellites pass overhead in sunlight while we're in darkness and if everything is perfect you can see the sunlight reflect of their solar arrays for about 10 seconds. The intensity (magnitude) of the light varies depending your position with respect to the solar array's position.
The highest magnitude you can see from an iriduium flare is -8. The brightest object in the sky is the moon at a level of -12.7 at full moon and the next brightest is venus at -4.4. Following the scale... An iridium flare is about 100X dimmer than the moon and about 65X brighter than Venus. Bottom line is that it's really cool to see.
To find out when you can see one check out this web-site. It's pretty cool in that you can put in your coordinates and it will tell when and where to look to see the next iridium flares for the next 7 days
BTW, my astronomy is very limited so feel free to correct any mis-information I have given... I do believe everything is correct though!