Large white spherical pulsing object in distance

I was looking up at The (almost) Full Moon and thought I saw a comet/meteor. I continued to look up and saw a very large but distant white, circular object that "pulsed" very brightly for about 2 seconds... Then it disappeared and pulsed again about 20 seconds later, then again appeared and pulsed about 35 seconds later. The movement was non-linear and the time between pulses was not regular. I watched it pulse and move "down" the sky until it disappeared from my sight behind the line of trees in my yard. It did not occur to me to photograph the occurrence because I was so fascinated just watching. Duration of event: 3 minutes.