I saw lights in a triangle shape decending straight down and a red light came on as it went behind the hills.

In December, 1977, I was on my way to a dance in Richland center, WI. Somewhere near Muscoda, WI, I looked out my drivers side window as I rounded a right curve and saw 3 lights in a triangle coming straight down out of the sky. I would approximate the distance from me to be 1/4 to 1/2 mile away from me. There was no airport in the area , it was not a plane and it was decending to fast to be a helicopter. It also did not have a beacon light. The landscape to my left dropped into a short low area and then rose quickly to hills 3 or 4 hundred yards from the road. It was dark, so I could't see the shape, but the lights were in a triangle. Just before it dropped behind the hills, a red light came on in the center of the triangle and stayed on as it dropped behind the hills. I was late already for the dance and didn't stop to investigate, but to this day, I sure wish I had.I hope to see it again someday...
Witness indicates that date of incident is approximate.  PD