Large round, UFO spotted in California

I thought that I was watching an airplane on route from SFO airport. The object looked like a very large plane flying fairly low in the sky, coming in my direction as a large, bright, slightly orange glow. Airlines normal come from this direction but as the light approached, I noticed that there were no flashing port or starboard lights, that would normally be seen on an airplane flying at night. I watched the light and the then noticed that the light began to zig zag in slow motion across it's path. As the light got closer to my property,(still zig zagging) it began to climb slowly. Suddenly, the light, changed it's direction and shot off at a tremendous speed directly up into the night sky and disappeared.