It was around 11pm & i was standing on my roof overlooking san francisco. i was looking at stars & jupiter to the south when i spotted 3 dark grey circles (less dark than rest of sky) arranged in an equilateral triangle travelling silently at high speeds from the w/sw and towards the ne. although these lights were already travelling rapidly, they accelerated upwards and to the ne rapidly with no sound. since i live near sfo & oak flight paths, commercial airliners were also visible in the sky at the same time. three things stood out that made this sighting significantly different than any other plane/craft i've ever seen in the sky before: (1) rapid speed & incredible acceleration, (2) absolutely soundless/silent operation (2) no illumination or lights on the craft. this object flew & accelerated rapidly upwards & disappeared out of sight towards the ne (over downtown san francisco or perhaps already over the bay… the 3 dark grey circles became too far away too see – it was dark outside & the object was not illuminated by any lights). based on my google & youtube searches for similar sightings, i believe i possibly could have seen the underside of a b2 stealth bomber as it flew back over sf from a flight over the pacific.