Large fireball moving slowly, horizonally, very low in the sky, lighting up everything for miles around.

I was living in Pleasant Hill, CA. I was about 24 years old then. 
I had my two babies sleeping in the back seat as I was driving home from Sacramento very late. At that time I was the only one on the road. This road was Hwy 780. It cuts off from 80 to 680. 
There are no lights along that road. To my right there was a cut away in the hill so that I couldn't see to my right. On the left was a very large marshy meadow. In the distance were many homes. It is impossible to see the homes in the dark from there. 
As I was driving along suddenly the sky from above me lite up like it was flood lights right on me (almost like daylight). It really startled me. 
I looked to see where it was coming from and finally saw this huge ball of fire about 50' above moving horizonally over my head from my right to my left and out across the meadow lighting up everything in its wake.  I could see the entire meadow and the houses in the distance. It wasn't going very fast. It wasn't falling. 
I didn't stop to watch it any longer as it was really scareing me. 
If it happened today. I would have stopped on a dime to watch it.  
I did't see what happened to it after I watched it move over the houses.
 The ball of fire was probably about 20 to 30 feet in diameter. I only watched for about 3 minutes. It looked just like fire.
Witness indicates that the date of the sighting is approximate.  We have assigned an arbitrary date above.  PD