Single, bright white light over Rapid City, SD.I live about 10 miles from an Air Force Base that has B-1B bombers. These planes are very loud and unmistakable. I also live about 5 miles from a regional airport. I have prior military experience with aircraft so I have more than general knowledge regarding general aviation.On the night of May 17, 2009 around 11:30 pm I stepped outside to smoke. It was a clear night and the stars were visible. I noticed a single bright, round, white light at about 35,000 feet (or more) in the sky to the north and thought it was a plan. I looked up and it just continued to get brighter and quickly disappeared. There was no noise and the color and shape stayed the same. It almost seemed like the light was coming closer and just turned around and went up and was gone. It took about 4-5 seconds.I have never seen anything like this in my life. It wasn’t a plane, satellite, or shooting star. I wonder if it was a dying star or even a UFO.