It hovered above us several thousand feet maybe-metallic appearance about 30' wide and disk shaped

This was very memorial to me because it was my 25 th birthday and we headed up Blue Ridge Parkway after getting off work at 5 PM Daylight savings time. My husband saw it, stopped the car surprised by the UFO, so we could both look up. It was up maybe 2000 feet but silent with no exhaust, but I thought maybe a slight vibration. When it left heading north, it went faster than anything we have ever witnessed. I thought it might have been so fast that it literally went past the mountains, but that did not happen. It seemed to wink out of existence. There was a military jet flying on the western horizon heading south that was so slow there was no comparison. This was 1977 so don't see how humans were inside. It also felt weird like sensing an intelligence. Memorable experience!