My wife and I had just got home from the coast and she was getting ready to go out to the movies with her sister, I went outside to call my dad to say hi and have a chat like I do every week, I was walking around out the back of our unit complex in Curtin ACT, It was around 19:30hrs when it was dark and there were storms around the Canberra area. I looked up to watch the lightning going off in the distance when I noticed a plane going across the storm clouds heading south west / westerly. What really caught my eye was the bright light flying behind the aircraft, It was zig zagging in quick sharp movements back and forward about 100m of the back of the aircraft. I watched for about a minute in awe then finished on the phone to my dad, mesmerized by the sighting I realized I should get my wife I ran to the window and got he attention and told her to come out and look at this, when I turned to look back at the aircraft and the bright light the light stopped for a second and then shot off into the storm clouds. unfortunately my wife didn't get outside in time to see it.When I first saw the light behind the aircraft I thought it may have been another aircrafts front light until all of the zig zagging then I realized this was some sort of craft that we do not have the technology for.I was amazed and felt so excited because I have always been interested in ufo's and any unusual phenomena. In my life I have seen many things I cant explain including ghosts and other ufo phenomena which I would love to share.