Blocking out stars ...800 x 2500 meters! Right overhead pasing slowly, No noise,feeling of pressure,just before apperance, verry low lightningstrike in clear sky.It took 20 minutes to pass over us and we started feeling afraid and depressed in the process,NOT exited!Collosal,no lights,no reflections whatsoever.Island of Thassos northern Greece.Never spoken of before.((NUFORC Note: Witness indicates that the date of the incident is approximate. PD))