Around 5:55pm my roommate and were on Shadow peak and cheyenne when we saw what we thought was a spotlight from a helicopter shining over the Red Rock area towards the east. It then lifted at a higher altitude heading towards the west. What we thought was a bright spotlight beam ended up being some sort of dust or smoke that seemed to linger even though the ufo was still visible high in the night sky but nowhere near where we originally saw it. This lasted about 12 minutes and we ended up stopping near a park off of Cheyenne and the 215. The white haze was noticeable from a SW area but the craft was not. It was the smoke or dust that had concerned me the most.