on this date I was working in a garden when I looked up and saw an aircraft. It was totally clear, no clouds and it was flying in a straight line at approx 50,000 feet, far above normal air traffic. It glistened in the sun which is what drew my eyes to it, suddenly it disappeared, sort of melting into the blue sky. There were no clouds and it simply disappeared. I continued to look in the area where I last saw it but it never re-appeared. It was so high, I cannot give a description except I noticed that it had no wings. I was traveling at a normal speed gauged on the normal speed of a commercial airliner. I watched as it disappeared; it was like looking in slow motion, a gradual fading into the blue background.