A soft white couple of opposing chevrons flew silently over.

I am a sober middle aged man with glasses. I haven't been diagnosed with mental illness nor ever had a hallucination, to my knowlege. I was outside on my front porch which faces West when movement in the sky drew my attention.
 I saw a soft white series of lights that looked more like reflections of moonlight than self luminous. There seemed to be two chevrons, one pointed forward and one pointed to the rear at a slight askew, upwards angle, with a distorted, perhaps reflective area between. It blocked out the stars and hazy high level clouds as it passed but some distorted lights seemed to be reflected in the area between the chevrons, which I assumed were reflected city lights.
 It's size was slightly larger than a silver dollar held at arms length.  Within 4-6 seconds it passed from about 40 degrees to the Southwest to 45 degrees to the Northeast where it faded from sigh. It made no sound and there was no way to judge speed or size, other than getting an impression that it was larger than a private plane in size and much faster than any normal aircraft, but I cannot say with certainty.
 There were no standard navigation or running lights and I am fairly familiar with aircraft. I am convinced this was something unusual.
 This was over Tucson, between downtown and the University.