I was outside of my house,admiring the night sky,when I noticed an object streak across the sky and then stop very quickly. Then another object came up very quickly and stopped perpendicular to the first object. Then very slowly they took off.They did some unusual maneuvers that any known flying object can't do. This went on for 2 hours, until they (in the blink of an eye), disappeared.They were changing in shape.What they did in the night sky of northern sky of Montana,seemed almost like a dance.They were both a pulsating yellow. The Montana sky is know for it's clarity, so I know that I wasn't seeing things.This went on for two hours.