I looked out my window to see a disc shaped object hovering about less than 100 ft. over my house.

This happened when I was only 7 but I can picture it like it was yesterday.  On hot nights when I couldn't sleep I would put my face up against the window that was right next to my top bunk because the window was always cooler.  One night I did this and opened my eyes to see a disc shaped object hovering less than 100 ft. over my house.  It was all lit up in different colors and the lights kept flashing in a pattern.  My parents were sitting on the couch in the next room talking and I called out to them asking them what that thing in the sky with all the lights was. My mom didn't even look out but called back that it was an advertisement and that someone was having a sale or grand opening.  At the time, being only 7 this made perfect sense to me, but later I realized that from my discription she thought that I was talking about a strobe light.  It was at this time that I realized that that thing that I had seen was not anything the average citizen was familiar with. As I watched this object it slowly and silently started to "drift" in a slightly NW direction towards the Ridge Road viaduct just East of Wicker Park, until it was out of sight from my window.  Years later I was talking with a friend who had lived a few doors away at the time and she described for me the exact same thing even though we had never discussed it before.  She had seen it too.