I was walking home in Preston, UK at night when I happened to see a weird light formation on the sky. First I thought it was a plane, but the lights were more in a triangular kind of form than airplanes usually are. Also, their speed varied and at times their speed slowed down tremendously.I'd say there was about ten of those lights, but some of them went off towards the end. The lights sort of faded out one at a time as they moved further. I tried to take a picture of the lights with my phone but I was a little late to get a good one. I don't really know what to think of this, but I got pretty excited about what I saw. I'm definitely doing to look up online if there'd be an explanation for the phenomenon.After spotting the sighting I called a friend to come check them out but he could see them anymore from where he was at that moment (about a mile away).