I observed a green orb gliding north to south about a hundred feet high.

I was at work as a security guard, driving a patrol car through a residential complex at 4:36 a.m. with my flashing yellow lights on, when something caused me to look out my left window. I looked up and saw a small green orb slowly gliding silently towards the south [I was also driving south]. It was about 1 hundred feet up, and almost overhead. Right after I observed it, it sped up, as if it knew I noticed it. I jumped out of the car, never taking my eyes off of it, and watched it speed off due south, maintaining the same altitude, and traveling in a straight line, until it faded into the distance. It never made the slightest sound, and it glowed a "traffic light" green color.