I were on a beach with ny daughter. we had a kite that was fling over my heads. the sky was brigth and completely clean (no coluds, airplanes, helicopters and son on). it was in the late morning between 11:30 and 12:00 am. at a certain point, near the kite, i saw a black object in the sky. i think it was 4-5 chilometerer up in the sky. i kept observing the objiect because it was completely stationary. it did not move in any direction. the shape was not clearly visible, but it looked like a cylinder, sligtly inclined on its major axis. i looked at it about to minutes, when, then, something very strange happened. the object emitted a bright light, as a flash, but not like a lightbulb when it is swithed on. the light started from one side of the object to go to the opponent side. after the flash, the object completely disappeared. i kept looking on the air for some minutes but i did not notice other phenomena. no sound was produced by the object.