Triangular shape obscures starlight as it moves across the night sky

I recently watched a program about UFO sightings and one of the UFO configurations reminded me of an object I had seen in the night sky fifteen years ago.  One does not report such things unless he is willing to be scrutinized.  I was not so willing.  I am grateful that I can share this anonymously and be taken seriously.
It was mid summer in Beloit, Wisconsin.  Some friends and I were sitting around a bon fire that night talking and laughing.  I enjoy looking up at the stars, wondering what else is out there and who.  As I was gazing into the night sky something, a shape, caught my attention.  There were no lights or sound.  There was only that large triangular shape obscuring the starlight as it glided stealthily across the sky.  If you were to hold your hand up, it would have been approximately half the size.  I watched it move silently for about 45 seconds.  It didn’t move fast, but it maintained a constant speed.
My mind raced for a logical explanation, but I could find none.  I thought perhaps it was a stealth fighter plane.  I then deduced that it would have moved faster and made some sort of sound as it passed by.  Not to mention, it would have had lights being over U.S. soil.  I also thought about telling my friends, but I didn’t feel comfortable with being called crazy or told I was just seeing things.  That was the only time I saw an object as such, yet I still stare up at the sky hoping that I might catch a glimpse of it one more time.
I know it’s not much, but it is what I saw that night.  This is the first I’ve even mentioned it.  Please, do not take this as a hoax.  I know what I saw and I know we are not alone.
Sincerely,  Sky watcher in WI
Source of report indicates that the date of the incident is approximate.  PD