Parked in car on isolated road, object with flashing lights desended over the car.

It was the summer of 1978, the month and day are approximate to my best recollection, as this happened over 20 yrs. ago. The event took place on Dell Road in the town of Heath, Mass, approximately halfway up the road. I owned property on the left side of the road at that time and a friend and me were basically just camping out on the properyt and parking alongside the road. The location of the event is fairly close to the Rowe Nuclear Power Plant and sightings at that time were very common around that nuclear power plant, unfortunately at the time there was no way to report such encounters. My friend and I had come back from Greenfield a little before 10PM after getting dinner and had parked in the location described (right side of road facing uphill). We were sitting in the vehicle (I was in the driver's seat) listening to the radio and relaxing when we suddenly noticed swirling lights all around us. It kind of startled us, we thought maybe a police car had pulled up behind us and was wondering what we were doing parked in such an isolated location. At least that was my first thought and my first comment. We were facing uphill and know there was no vehicle in front of us. I thought it had to be behind us, I rolled down my window and looked to the rear of the vehicle and there were no other vehicles on the road. I then looked up and there was a huge, very huge, object just above the treetops covering us and both sides of the road with lights underneath, the only way I can describe the lights are flashing and swirling. The exact size of the object had to be at least 40 feet in diameter and absolutely silent, it made not one bit of noise! At that point, I rolled up my window, started up the vehicle and slammed it into gear and took the uphill road with the pedal to the floor and did not look back. When we got to the top of the hill we parked at Heath Center, just past the town hall. At that point we weren't quite sure what happened. We just watched up through the windshield up into the sky! We felt a little safer being in the proximity of several houses rather than an isolated road.
That was the first experience I had there, but there were more to come, which I will also post on here.
Date is approximate.  PD