My girlfriend and I were sitting in the hot tub to look at the stars. We have a pretty good view of the flight paths of the planes that fly over to the local airport and the ones that head across the ocean. We have spotted many satellites and planes at many different altitudes over the years. This night the sky was clear and the Milky Way was slightly visible. When we first spotted the ufo it was approaching from the north west west horizon. Where it approached from it had the setting sun and the thin crescent moon (which both had set) well behind it so we were both surprised that it was so bright at such a spot in the sky. As it approached us and got more overhead I noticed that it was making a large slow arc towards the east. It was larger than any star in the sky and brighter than any satellite I've ever seen. It didn't loose any of its brightness until it was almost above the horizon to the east. It did not seem to drop towards the horizon like a plane does when it flies out of sight. Shortly after we lost sight of it there started lightening flashes in the direction that it disappeared. We didn't hear any thunder or see any clouds the whole time were were outside.