Flying strobe lit object travelling at very high rate of speedAt approximately 11:30 PM ET on 10 May, 2015, I walked out onto my back screened porch. The weather was clear and no moon was present within my field of view. Standing out on the porch facing south, I noticed a white strobe that flashed three times within a two second period. What made this seem so unusual was the large amount of space between the location of each strobe flash as the object traveled from east to west. A few seconds later, I saw the strobe flash three more times but the distance the object had traveled during the second set of three strobe flashes seemed extreme. I continued to watch and saw the final three strobe flashes to my far right as they disappeared behind some trees in the yard next to me. Looking up into the sky, the distance between the first time I saw the strobe until the second time, I estimate the object traveled across about 20% of the visible skyline/horizon. There was no noise from the object. I cut through my house ! and went out the front door to look to my west to see if the object had appeared on the other side of the trees, but it was gone.I retired from the USAF with over 28 years and the only time I have seen anything pass by so quickly was watching a low-level F-15 fighter jet fly-by at sub-supersonic speeds. If it were a jet flying at subsonic or supersonic speed, there should have been some engine noise. I estimate the object had to be higher than 3,000 feet above the ground. The angle of the flight path above the horizon was around 50 degrees.