Blue-green shifting colored fireball lookalike object flying at a relative low above sea level at a very high speed in Finland

Blue-green shifting object, flying at a very (tremendous)high speed across the horizone, in a straight direction. It was very difficult to estimate the height of the object as it passed above the sea and the forrest. I would still believe that it was about 200-500 meters above sea-level. Many people saw it because we were waiting at the pubblic car-ferry to take os from one island to another in the finnisn (Finland) archpipelago. I am sure it was not an army aircraft (like the F18 Hornet) because of the speed and colors of the object. Later on the same day we contacted the Flight Controll at the airport of Turku in Finland and they told us that similar observations had been made more north in finland during the same time and day. Anyway, they told us that it was "Space-Trash", I do not know what that means but that´s the explanation they had.
Thanks, Mr. Finland
Witness elects to remain anonymous.  Date may be approximate.  PD