I was at Arbor Lodge Park in North Portland, OR on August 17th, 2014 for a Movies In The Park event. They were showing "Back to the Future". It was about 9pm, right before the movie started, and I noticed a light in the sky to the West, off in the distance in the direction of Forest Park. At first I thought it might be a police helicopter in the distance, but the light colors started changing (between white/yellow, red/orange and light blue/white), although the exact hues are a bit fuzzy as it's been over a month since the event. What I clearly remember, so vividly that I felt compelled to share it with someone, ANYONE, is how is started to zip around the sky. For the next fifteen minutes or so, it would zig and zag across the skyline in a manner that just baffled me. It would stop every so often and just hover for a few minutes, then with no warning, shoot across the sky in different directions. It was as if someone had a laser pointer pointed at the sky and was just playing around with it. I tried to talk with my party about it, but they all seemed more interested in the movie. Eventually it zagged behind the inflatable screen they were playing the movie on and i settled into watching the movie, checking the sky a few times later, but seeing nothing. I don't know what that zipping light was, but I've never seen ANYTHING move like that in the sky. I really don't know what to think about it.