Bright white light from U.F.O.

When I was young boy around 10, I would sleep outside in the summertime to enjoy the cool night. 
One night I saw a slender ovular-shaped, bright white light, which seemed to emanate or radiate out from below.  So I figured if I could be underneath it, it would probably look like a saucer (circular) shaped craft.  I also estimate it was really long, because the Uptown are of my Hometown is probably a couple miles from where we lived back then.
I walked up the steps to the new deck to get a better view.  It was just moving across the sky horizontally (over or behind the Uptown hills of my hometown, maybe one hundred feet off the gorun ((sic--ground??)) or more).  Then it stopped, then ascended, until it looked liked it left our atmosphere.  I can't remember now whether it was moving away or going towards Concord Naval Weapons Station.
I still feel bad because to this day I wish I could have waken my Mother and Step-Father, because I could have knocked on their sliding-glass door.  But I was so in awe of this craft, all I could do was stare at this object moving across the sky.
I now think that either it was extra-terrestrial or a Government U.F.O. since Popular Mechanics did an article that said our Government has mini-reactors in these U.F.O.'s and that traces of spent nuclear material has been found where these craft land.
Witness does not indicate the date of the incident.  We wonder whether he might have been witness to a missile launch from Vandenberg AFB.  Not knowing the date of the event, we cannot determine whether that might have been the case.  PD