There is nothing better than a detailed visual aid to help me really understand what a UFO looked like. Here you can see what one person witnessed, over an Oregon town. Some, the artist admits, is extrapolation.
According to Lights In The Sky, a Texas blog about UFOs, these images come from a MUFON report about a UFO sighting in Bend, Oregon, earlier this month. They write:
The witness from Bend, Oregon, who when returning from a football game saw a triangular UFO, has submitted drawings of the object.
Sounds like a pretty well-lit UFO.