massive triangular shape craft moving silently across clear night sky.

i was walking down a flight of stairs and looked up to the sky noticing 3 lights that seemed to fallow each other moving west to east ran back up to apartment to get a friend to see what i was seeing we ran down to the street looking in the southern dirrection watching it silently move west to east must have been about half of a mile long as it faded we could easily make out a triangular shape massive in size.  the 3 lights were very dim but constant. (not blinking)