Very large silent slim chevron aircraft over Downey CA 1979

The night was clear and crisp. Patches of low level "cottonball" type clouds, and lots of sky in between. Something caught my eye and at first I thought it was a "search light" moving across the clouds, but to my astonishment it was a VERY large chevron aircraft skimming the tops of the clouds. It made no sound. This occurance happened over the Stonewood mall area which at that time had those sodium street lights, they look orange.
The aircraft was smooth on the bottom and low enough to make out detail. It had no markings, no engine nacells, windows or bumps of any kind. Its color was tan as I believe it was reflecting the street lights on its belly. It had no lights at all. I started counting seconds right away. Total event duration- 12 seconds.
Date may be approximate, although the witness does not indicate that fact.  PD