Saw bright "star" that changed into red, white, and blue lights. Emitted a beam of light in a horizontal sweep of the sky. Darted horizontally, vertically, and diagonally across the sky.I was out looking at the beautiful Montana sky one clear night, when my eyes caught an unusually bright star. I thought nothing of it, but when I turned to look at the same spot again, the "star" had moved. Then I looked at it from the corner of my eye. It started to move again, but as soon as my eyes focused on it straight on, it stopped, like it had never moved. I stared directly at it, and less than five minutes later, it started to shake. Then it darted across the sky, where it stayed for a few seconds more, then took of in another direction. All together I watched this "star" for over an hour and half. It had no regular flight path, and stopped, accelerated, and turned much too quickly and precise for any conventional aircraft. The longer I watched this, the more I began to notice. It would change from a bright yellowish-white light to red, white, and blue lights. It would also dart across the sky, change direction, and emit a faint white beam horizontally, in a 360 degree sweep of the night sky. Sometimes the light would get brighter, then slowly fade out and disappear, only to reappear in the same spot a few minutes later, like it had never moved. Just last week, on May 12, I was standing on the top of Big Mountain, a ski resort here in Whitefish, and witnessed the same thing again.