Enormous triangular object blocked stars as it moved slowly over house

This event happened many years ago but I still have a clear picture in my mind of the experience.  It was recently revived when my brother-in-law who I did not know in the early 80’s told a story that matched mine identically.
In 1981 or ’82, I was standing on our front porch in Missouri talking to my son and a friend who were about 12 at the time.  It was after dark and the weather was warm.  Suddenly, we became aware of something above us and I don’t recall any noise.  It was a starry, clear night but we looked up and could see no stars directly above us even though we could still see stars towards all the horizons.  There were lights traveling in a triangular formation so at first we thought that three planes were moving slowly from the southwest to the northeast.  We finally realized that the lights were outlining a huge single triangle shape which was blocking the stars from our view.  It lasted only a few minutes before it moved slowly beyond the tree line, but was long enough for us to discuss it.  Afterwards everything returned to a clear starry night.  We wondered if it was an experimental craft from a nearby military installation but thought it was too large to be anything we had ever hea! rd about.
Recently, my son’s friend who is now the CEO of a corporation asked if I remembered that night and our encounter with a UFO.  Then my brother-in-law recounted the time in the early 80’s when he was dining at a table by a corner window in an exclusive restaurant on the 22nd floor of a building in a nearby city.  It was a clear starry night when suddenly he became aware of something moving towards the building from the southwest that was triangular and enormous.  It blocked the night sky and had lights at the points of the triangle.  He and his party thought it was going to collide with the building but it moved over the building and all returned to normal.
Witness indicates that the date is approximate.  PD