Many miles up in the sky;zigzagged;sharp - immediate change of direction; very fast

One night during the summer of 1965 when I was not quite 13, I had a friend over and we were in the house. My mom and dad and uncle were on the back deck visiting. My mom called me, my friend, and my older brother to come outside to see something. I looked up and found what they were talking about. It was a light way up in the sky, not as bright as a satellite, more like a small star. This light was zigzagging in a pattern. At the time it seemed like it was moving so slow, but now I realize how fast it must have been moving. My parents and uncle had been watching it for quite a while before they called us outside. I watched this thing zig zag across the sky for at least 30 minutes and then it took off very quickly in a straight line and disappeared from our view. My uncle was retired from the Air Force and he ruled out all aircraft he knew about.
Date in summer of 1965 is approximate.  PD