A huge lit-up craft various colors of lights at tree top level traveling at a very slow speed (10 mph) over our heads .

My mother and I were traveling a short route home (5 min. ride)from my grandparents house when at a stop sign at the intersection of Arch road and West Avon road A HUGE lit-up craft appeared out of nowhere at tree top height (approx. 50 feet) going very very slow over our car. We got out of the car a looked at it in amazement I have never seen anything like this in my life to date (this happened about 22 years ago I was about eleven, and remeber it very distinctivly). I had made mention that the craft was "lit-up" it had various colors of lights and was traveling at a very slow speed (running speed, 10 mph) it creeped over us heading in the direction of a cow field adjacent to the road we were on. no noise what so ever.
Date may be approximate.  Witness provides a paucity of personal and contact information, but describes self as someone with considerable technical background.  PD