I first saw this as I was parking my vehicle. It looked very strange for an airplane taking off early from the Boulder Airport. I jumped out of the truck and observed the colors and straightness of its path towards the foothills. I DID NOT observe any flashing red lights that you would typically see on an airplane when flying in the dark and did not hear any airplane noise.It had an amazing yellow sparkle looking tail. I knew it was probably not an aircraft and was delighted to have seen this. It was easy enough to see in the early dark morning hours.