Glowing triangular object, composed of smaller triangles, floated silently across sky from NE to SW.

Summer night in Fargo, ND. Wind unusually calm. Cloudless sky. Year was approximately 1978. Sitting alone on the deck about 11 pm, I saw A triangular-shaped glowing object, composed of smaller triangles, floated silently from NE to SW over the roof of my house. It went in the direction of the triangle's point. I ran to the SE corner of the house to see it emerge from the other side of the house but did not see it again. Could not tell how high it was; if it was within 50 yards of the roof, it was about 30-50 feet long; if it was higher, it was much bigger. My background: college graduate, never have done any drugs, never smoked anything, very light drinker. Always have been interested in aviation/ aerospace. At the time I was in my mid 30s with a husband and two young children. My son, also always interested in aviation/ aerospace, is now a pilot for a regional airline.