During the Phoenix lights I was walking the mountain preserve adjacent to my parents house. I first noticed a large dim light moving from north to south. I observed it for about 30 seconds then realized when it was overhead that it was one of 7 lights in formation. The light was less luminescent than city lights but very large. It was about the size of a football field at 500 yards away. The light was circular. The distance between the light overhead (which was the last in the series on the right wing) and the next towards center was about 5 times the circumference of the light overhead. I saw 6 other lights, the last, on the left side was barely visible. If the light directly overhead was 500ft in elevation than the width of the ufo ~3500yards? The space between the lights looked solid yet seemed to refract light around it leaving blurry stars but seeming solid.