observed a very long craft with a cheveron front. Front of object had several dim lights, craft very large, moving slowly over pasture

In the late summer of 1980, a friend and I were sitting on the trunk of my car  at approx. 11:30 p.m.  My home was located in Brenham, Tx,-right off of the highway, ( sorry, can't remember which highway) and was surrounded by cow pasture.  We were just looking at the stars..and suddenly we saw a strange craft moving slowly through the night sky, directly above us.  We thought at first that the object was a blimp-soon it was quite obvious that this was no blimp, plane,etc..The object was very, very long..at the very least one football field in length.  The front of the object was chevron/triangle shaped, with dim lights all along the rim of the front.  Object was very slow and seemed to be flying at low altitude.  The oddest thing was the complete absence of sound-any object that low, that large would have to make sound of some sort, but this thing was totally silent-almost like a vaccum- everything was incredibly silent.  We watched this for approx. 15-20 min, in total shock, not really believing what we were seeing.  We never reported it, never mentioned it to anyone-as we were young, ( 20) and knew that we would never be believed.  To this day, I believe we saw an alian craft--I am now in my 40's and have never again seen anything that large be able to fly..and especially be totally soundless