I was driving from Thornton to Commece City on 120th Ave and saw 4 bright white, pulsating lights standing still in a curved shape in the sky, They were in the same spot for about 15 minutes. Then the lowest one slowly descended to the horizon. I was in the car and could not see where it seemed to have landed. A few minutes later, the highest one did the same thing. Then, finally the other two did the same. They all seemed to have landed in the same area. Looking to my right, there was another much higher in the sky that didn't move. I thought they were airplanes until minutes passed by and they were all in the same spot, making the same shape, and compared to the airplanes in the sky, they were much larger and the light was whiter and not blinking but twinkling. This whole time I was wondering if anyone else was curious about them.