I was outside the east side my house listening to the Cowboy/Eagles Sunday night game, just after halftime facing west. I looked up over my head and saw, coming from north to south, a formation of triangles. They were perfectly arranged and stayed in their orientation through the whole sighting. Each triangle looked like it was outlined, with the only light visible being on it's edges. It gave me the impression that these triangles were fixed on something but I couldn't see any shape of a craft. I put my hand up and figured the size to be that of just under the size of a quarter at arm's length. When I first saw the triangles they were approximately 20-25 degrees north of me to my right. I watched the formation travel to the south for about 6 seconds then I had to move to south side of my house because the formation went behind my roof line. I saw them immediately when I got to the south side of my house and continued watching them travel south for ten seconds more. When the formation was approximately 45 degrees from me it changed directions and headed west into Mexico. It did not turn or reorient itself. It simply went west at about 90 degrees from it's previous flight path. The peculiar thing was that it's flight time across the sky did not appear to change speeds as my angle to it increased it appeared to still go as fast as it did when it was straight overhead. After it changed directions it accelerated and was gone from view in about 2 seconds. There were no flashing or colored lights. I couldn't see any form of the craft. The triangular light formation did look very much like it may have been on the bottom of the craft as they did seem to visually be tilting away from me as the angle of view got greater. The best way to describe what I saw was to think of nine florescent tubes in groups of three touching ends together to form three triangles, placing the triangles apart so that one side of a triangle lines up on the line of another at least 4 or 5 side distances apart. The triangles formed a perfect triangle. At no time did I see any stars between the triangles. There was no sound coming from the craft while it was in transit or after it was gone. We have high flying commercial airliners flying into Mexico pretty much every day and I can't hear their engines till they are about 15 degrees from straight overhead. This formation may have been outside the atmosphere. I have never seen anything like this before. But I'm so glad I have seen it.