Iridium flares are a little harder to observe but a lot more fun.
Imagine a scenario (like I've experienced many times before), where you are standing along the streets somewhere and you are staring up into space. People are walking past you and they are wondering what you are looking at. They look in the same direction and they see nothing except empty space. And they think maybe that's what you have between your ears, too much empty space.
For the few who'd dare, they'd probably walk up to you and ask you what it is you are looking at. You tell them to hang on for a couple of seconds and keep watching at that exact location in the sky. Just then, a bright light suddenly appears! It lingers for a few seconds as it streaks across the sky and then it vanishes. Everyone is a little surprised and they are all wondering what that was. As they turn back to ask you, they realise that you have already walked away. Cool? Well I think so.
What they don't know is that they have just witnessed a flare from one of the many Iridium satellites we have up there. Basically it's just a reflection from the sun on one of it's antenna panels. These flares reach a magnitude of -8. In effect making them the third brightest object in the sky after the Sun and the Moon!
Iridium Satellite and what causes the Flare.
image : satobs.org
Go ahead and make this a hobby. It is really fun. You can locate the next flare in your area at http://www.heavens-above.com/. Just key in your location and you are done. Absolutely free. Amaze your friends with perfect prediction. Every time. Remember, some of this flares are so bright, they can even be observed in the daytime! Read more about them at that site or even Wikipedia.
To observe, you only need a basic compass and the simple ability to gauge inclinations or altitude.