Light seen over Auburn Ca.While driving east bound on I-80 in Rocklin I saw a light blue-green light. At first I thought it was an aircraft but realized it was moving much too fast. It moved from South to North. I had an unobstructed view of the sky. The light suddenly appeared and traveled downward at about a 30 degree angle to the horizontal until it disappeared at my horizon line but in front of the backdrop of the Sierra's. It traveled in a straight line. There were no red/green/white marker lights to be seen. Had it been a meteor, it appeared to be headed for Auburn. As I drove through the area, there was no emergency vehicle activity to be seen. There are no airports in the area that could accomidate a plane that was this fast. There was no "tail" indicating atmospheric ablating of material as should be seen from a meteor this low in the atmosphere. After returning home at 19:20 I checked off my back deck for any signs of fire or other activity. There were none. From my back deck I can see about 50,000 acres of the Sierra Foothills along with the entire North Sacramento Valley.I am an engineer, amateur radio operator and pilot.