Looking from the plane window I saw a golden ball fly in a straight line before descending into the clouds.I shouted a friend of mine who was sitting opposite me across the isle, but the ball vanished before he could get across the isle.At the time we must have been flying at around 30,000 feet and the ball seemed to be lower than the plane, although I could not say how far below the plane.A very short time after seeing this ball, a jet went by our plane at a very high speed.I could not tell if this was a Chinese military plane, or if the plane had anything to do with the ball. I was not shocked or surprised by seeing this as I have had quite a few sightings while I have lived in China in the last six years. This was at around 8pm on the 17th May half way between YanNang City and the city of Shanghai.I would be very interested to know if anyone saw the same as me on the same night.