Several classmates, science teacher, and myself were gathered on a hill behind the high school, after dark. We were there with a telescope to learn about the moon. I would say that less than half of our class had shown up. Perhaps 8 or so people.From left of us, facing the school, appeared almost unnoticed, a hugh triangle shaped object, moving slowly. It was dark but the lights outlined it as a triangle. I recall there were different coloured lights, but today could not say what colour they were. I do not remember any of the lights blinking.It was dead silent. It appeared to be quite low and massive. We all seen it, but strangely enough, it didn't seem to make much of an impression on most of my classmates???My science teacher called authorities the next day and was told that there was nothing that should have been flying/floating? in the area.It has been 30+ years, so I do not know if this report is any help. I had watched several shows on TV that described exactly what we had seen, so I decided to make a report, knowing now that this large triangle UFO sighting is common.The only technology I know of that could account for what I saw, would be some kind of blimp, however it moved steadily, too slow for an air-foil, and made no noise I could detect. I have excellent hearing.I have not spoken with the other witnesses about this. It is odd that we mostly ignored the event.