I was walking back from work, which is about 5 kilometres or so from where the sighting happened. Keep in mind I work until 1:00 A.M, so my sighting took place in the middle of the night. I always like to watch the clouds when I walk. I was following my usual routine of watching the clouds move, when I caught something out of the corner of my eye. It was a large semi-triangular object, and it seemed that it came out from behind the clouds. I thought it was a plane until I saw the flashing lights on the side of it were not the typical lights that you would see on an airplane. They were yellow, green and white and the flashed in a pattern of green, then white, then yellow, repeatedly. I would say the craft was approximately 30-40 feet long and 15 feet tall. it was moving in a fairly straight line. it started out going northeast, then made a sharp turn and headed true north until I could not see it anymore. It also made a unexplainable sound, similar to the sound of high frequency. Obviously at this point I realized I was not looking at an ordinary aircraft. I watched it until it disappeared. Then I ran home and now I am writing this report. P.S. I forgot to mention that I'm pretty sure it had 1 central rectangular window on each side of the triangle, although this may have been metal, or some type of pattern.