Strange light looking like a satellite moving slowly at first suddenly darts around the sky back and forth then stops.

My mother and friend and I were walking outside a populated area at night around 8:30 pm on the 17th of march 2007.  we stopped for a fire works display in honor of St. Patrick's day and it was a fabulous display lasting about 10 minutes.  
After the display was over we continued looking at the sky it was a beautiful clear evening.  Suddenly we were looking at an object that appeared out of nowhere it looked like a satellite moving in the sky.  satellite look like slow moving stars so thats what we thought it was at first. we commented on how cool it was to see such things like satellite in the sky, as our eyes followed the bluish looking star object drifting slowly to the right of us it suddenly darted to the left of the sky then the right then left again then hovered slowly and stopped. my mom pointed it out to our friend was a student pilot,  she said wow thats really strange planes do not fly that high or move that fast and satellite do not dart quickly across the atmosphere. 
 We left the area after the object stopped moving and just looked like another star in the sky. It was odd how it appeared to us after the fireworks like maybe the strange light was drawn to the area by the other bright lights.
I have never seen anything like this in my life and I can honestly say I have found no explanation for it but it definitely left me with a confirmed feeling to my core that we are not alone in the universe.