Seen light after coming back from the shop got out of the car good clear night 3 degrees in temperature. wife first seen light and then myself and our two children aged 9 and 12. a very bright light changed direction a number of times left right up down as pulse light and sometimes remained as a solid light other times flashed about every two seconds. i logged on to flight radar and no aircraft in our area were on screen for about 30 miles three commercial aircraft were due to pass behind us plane #1 london/new york heading west. plane number #2 to the front right of the house harstad/las pamas heading south. plane #3 tenerife/glasgow heading north. when the aircraft got closer to passing each other the light seemed to follow the two planes north and south bound for a few moments and then stopped. it is hard to tell height or distance so we can not tell what size it was but it moved at lightning speed at times to not moving at other times when it moved it was very fast it left a trail for a split second after the 20 minutes we seen it we were able to watch it slowly head south as a slow moving object until we lost sight of it.