Ball of light traveling at a high rate of speed over Keflavik Iceland, circa late summer 1998.I was walking with a friend down a side street in Keflavik Iceland in late August 1998 to go to the movies. The street was very wide, so I had an almost completely unobstructed view of the sky. As is my habit, I looked up at the sky because the sky is very beautiful there, especially in the late summer. Although it was about 7:00 PM, it was still completely light out with no stars or planets visible, the sky still a brilliant azure. There were a few scattered clouds. Suddenly, I saw a ball of light, but it was moving. It seemed to alternate between yellow and white in color, and it seemed to be quite high in altitude. I want to guess about 20 to 30 thousand feet (?). Because of the altitude, it looked to be about double the size of Venus, but not as brilliant, though it was bright. I could not see the actual shape, or if it was an actual craft, but it did appear circular. The shape remained constant, though the colors seemed to change. The main reason for this submission, though, is the rate of speed with which the object traveled. I first noticed the light when it was a little less than halfway across the horizon, almost directly overhead. It was completely out of sight in about 6 to 8 seconds. It also had a very flat, straight flight pattern, totally different from what you would see if you were watching a jumbo jet flying overhead, which tend to appear as if they are dragging across lazily the sky, hardly moving, and at an angle to the horizon. Speaking of jumbo jets flying at about 20 to 30 thousand feet, they seem to take forever before you lose sight of them, and they travel at about 650 MPH. Though I do not possess the mathematical expertise to calculate it accurately, I am pretty certain that whatever can race halfway across the horizon in less than 10 seconds at that altitude must be able to move at an alarming rate of speed. If it was something man made, I hope it is in the American inventory. As with my one other sighting, I was in a state of what I like to refer to as a calm astonishment, unable to speak out to my friend about it. I believe I mentioned it aterwards, but the response was pretty lackluster, as is often the case.((NUFORC Note: Witness indicates that date of incident is approximate. PD))