I was working my shift at ohare airport. i was recording a plane because it had my name across it and then i noticed something flying above the plane in a hoovering manner, so i zoomed in on the flying object. it looked like an orb but the way it was flying was abnormal for anything in the vicinity of the airport. i worked there for 3 years and have taken many videos and pictures of planes and the sky and never have seen anything like it. i would have kept recording but i had to assist a passenger and had to stop recording. i was recording through a window but the window was clear so it is not a shadow of anything and they say the way it is flying it looks as it is in the sky doing its own thing. ive asked alot of pilots for their opinion and they said it looks unexplainable….When i went back to record more it was gone.