I was driving home on the 421 Bypass in Harlan when two state troopers suddenly approached me from behind - one moved in front of me and the other stayed behind me (as if I was being penned in), when abruptly the trooper in front of me slammed his brakes. As I braked, in my periphery (to my right), I saw two red lights about 50 feet apart, hovering approximately 250 feet in the sky. For a split second, I looked back at the state trooper in front of me to make certain he was a good distance in front of me, then I looked back to where I had seen the lights (this took less than one second). Now, two green lights had joined underneath the red lights, and the entire light sequence rotated into a vertical position, as I lost sight of them. I was so excited (when I saw these lights rotate in a vertical fashion), that I turned around at the first chance I could turn off the highway, when I realized I wasn't being pulled over by the state troopers, and went back to see if it was still there. It was not.