I was watching a red light in sky...Quite low down north of kirkwall which i took as a local flight north to lerwick port light... it was rather brighter than i thought it shout be at low eleveation in sky....1st i saw a strobe but then it stopped...So did the red light....I just thought it might be atmospherics,,,but then i notice the actual a340 flight 2 lerwick was also in the sky...Which i saw overhesad....Its path was in same direction as the red orb i was observing....Then...The red orb...Moveved right (eaterly)...Which i knew could not be if it was a planes port light....Then it started to move excremeley fast! left(west) and wend behind a cloud. the pilots of the kirkwall->lerwick flight mustav seen it better.....Plus...I checked flightradar24.....The pilots of a helecopter flying southerly mustav seen that thing 2.......Probably much brichter.... please get back 2 me as 2 wot was there.... coggie. oh it was red....Prominant....And must have been miles away....But at the rate it moved as i seen it....Mustav been goin mach 10+ ?