I was at work on break watching a little bit of the air show from the roof at work that Luke AFB was puting on.I was watching the Thunderbirds flying.As they were doing a menouver flying straight up at altitude of around 15 to 20 thousand feet,i noticed a small bright white light fly right past one of the planes as they were breaking formation.It passed just below one of the planes moving from south to north.Wasnt going very fast and only appeared for about a minute untill i lost sight of it when it flew past the sun,i didnt see it anymore after that.I know for a fact that there were no other planes in the area as trafic is diverted away from the base because of air show.The Thunderbirds were the only ones flying at the time.Ive never saw a ufo in person before besides t.v. and finally i saw one.