UFO sighted while in-transit on southbound 101 near Asti

In early September of 1985, I was beginning a pre-calculus course  taught by one of my high school math instructors at Santa Rosa Junior College. Mr. S was also a good friend of my parents (my mother worked with Mr. S's wife), and with our familiarity, we  commuted to the night class 2 nights a week. One particular evening, Mr. S's wife joined the trip and remarked "What a funny looking light in the sky" in an unusual tone of voice. I've seen many UFO sighting in the area of Cloverdale my whole life (due to my love for stargazing), so I instintively reacted to her remark. Sitting in the rear seat, I craned my neck back and looked up at the sky through the rear window. It was fairly dark, the sky was quite clear with whisps of stratus clouds. Hovering over a grape vinyard/Russian River on the east side of HWY101 just south of Cloverdale near Asti. The craft was apparently motionless and hovering at approx. 500-600 feet. It was comprised of a large, central red light (which appeared dome like) surrounded by a cricle of numerous small white lights. The large red dome pulsated from bright to dim illumination while the ring on small lights flashed momentarily and sequentially around the red light. I could not ascertain as to what the shape of the craft was, but there was visible depth to the light formation, but the amibient light levels are fairly low on that particular portion of the highway. I continued to watch the object as we drove south until we went behind a spur of the local hills on the highway. At the time of the sighting I was 18 yeats of age, Mr. & Mrs. S were in their late 50's.