A triangle of three soft green discs passed us parallel to highway 50 in the Colorado desert which made no sound.

I'm a 66 year old Colorado Springs resident for 30 years plus. My friend from Denver was driving. We took a day trip down to see the Royal Gorge and then on to Salida and back. As we left Canon City the stars are always bright in that desert area. My friend said "What is that green light ahead" on the right side of the highway? I said it was probably that one flashy star that I can't name. He said "No. It's moving this way" as it was running parallel to the highway. I said ,"PULL OVER". I  thought my jaw would fall off. He had to continue a few feet as the shoulder was narrow. Then a driveway allowed him to jump out with me. My friend didn't have the view I had as he not only was driving and wears glasses.  I could clearly see a perfect triangle of three what appeared to be dimly lit discs which were not separate, but part of one craft. No clue what the vehicle itself looked like.  These soft green discs seemed more like what propelled it than marker lights seen on aircraft. It banked slightly left and the discs became obvious. It took approximately 15-20 seconds to pass by and head west from view.