Massive, moving behind ridgeline

Driving from Tennessee toward Cherokee, on a cloudless, sunny afternoon through Great Smokies National Park. I caught a flash of reflective light and looked out my driverside window toward the ridgeline. I was shocked to see a massive, silver metal clad object that appeared to be tracking with me in the same direction. It disappeared behind the mountain, and then reappeared as the ridgeline dipped and then disappeared again behind the next peak. I pulled over on the opposite side of the road, very shaken. My first thought was a jumbo jet was crashing, but then it didn't make sense in my mind. It should have made a noise, but nothing. It should have reappeared on the other side of the peak, but nothing. I did not see the leading edge or the trailing edge, no wings, windows or markings. It wasn't smooth but I can't say what the texture was I observed, only an impression of louvered panels maybe? The sight only lasted a few seconds. Those mountains are at an elevation of about 4500 feet. It was very low, the object was massive, as long as a foot ball field at least. I am an air force veteran, and I have never seen anything fly like this.