I happened to look out my back window and was shocked to see a huge triangular shaped craft at a very high altitude.I was in the Air Force for five years,but must say that the object I saw that day was unlike anything I had ever seen before.It was partly cloudy with some cummulous clouds but large clear areas.I happened to {for some reason}to look out the back window of the house,and spotted a huge triangular object at a very high altitude moving at what must have been a tremendous rate of speed.By the time I excitedly ran from the bedroom to the livingroom to tell my wife and son about the object{a distance of about ten yards}knowing it would pass by our large window,apparantly the object passed,as I only saw a mettallic glint as the sunlight reflected off it.I have seen many,many jets,both millitary and commercial fly at high altitudes;we are blessed with many clear,cloudless days here,especially in the wintertime.The difference was the comparative size of the object I saw and a jet at approximately the same altitude.I had a casual interest in UFO's prior to seeing the object,skeptical at best,but what I saw that afternoon literally made the hair on the back of my neck stand on end.Amazing.