While sitting on our back porch (which has a view for several miles over the Hudson river), I noticed that a red light in the distance (which I had originally thought was an airplane) had stopped suddenly and was hovering. I immediately pointed it out to my wife, and as I watched it appeared to "rotate" as the light changed from red to green, and then back to red. It then started moving again, instantaneously accelerating back to the previous airplane-like speed, moving for a few seconds before again freezing, hovering, and changing from red to green and back to red. Then it changed directions and flew back the way it had come from, until it was out of sight. We have regular airplane and helicopter traffic that we can see, but this object moved at LEAST as fast as the airplanes we see, and stopped and accelerated much faster than any helicopter I have seen. That being said, it was at night and the object had to have been over a mile away, making it impossible for me to see anything other than the light it was emitting.