It was impossible to tell. The was no visible light only what was being reflected off the craft by the extremely bright moonlight.

I popped out for a smoke and I usually look up at the stars, last night it was a beautiful clear night and I noticed what I first though was a satellite, but what I saw was too large, too low in the atmosphere and was moving too fast. It flew in a straight line from South to North, there was no sound or lights at all, it looked as though the craft was "gliding" across the sky.

Whatever I saw it was not meant to be seen, there were no lights displayed at all and no sound. It was difficult to estimate the altitude given the speed it was moving at and the size of the object. The object looked fairly large (at least a big as a commercial jet) and should have generated a lot of sound given the speed it was traveling at yet there was nothing!