lighted object with a strange motion. May have been livestock involvment.

This happened in the country about 2 mi. north of Alcoa. We were outside talking and noticed to the east of where we were this lighted object just hovering in one spot. The lights appeared to be flashing of some sort. All of a sudden as fast as you can move your hand above your head and as far down as possible this thing moved this fast and flew right back up just as fast. Up,down,up,down several times. When the thing flew up you could hear the cows in the distant 1 mile away mooing. After watching for about 1 hr. it started heading west toward us. I could no longer see any lights though as it moved directly over our heads we could see it was huge about the size of a football field only triangular in shape it was not that high in the air maybe 800 ft. there was no noise coming from this thing at all total silence I could even hear the crickets as it moved over top of us.
Witness indicates that date of incident is approximate.  PD