The object first appeared in the north sky. My attention was drawn to what initially appeared to be a shooting star. The first thing I saw was a flare of light moving at an extremely high rate of speed. I was essentially facing directly north when I first sighted it. The object was traveling downward and to my right (east). As I watched the object it appeared to change course slightly - flaring to a more horizontal trajectory that was now headed generally southeast. As the object changed course, I could clearly see a dimly lighted boomerang shaped object. The delta shape was covered with soft, orange colored lights. The fact that I was on a lighted residential street, along with the speed of the object and relatively soft lights eminating from it, made it hard to distinguish more detail. While it was not possible to see in great detail, there was no question of its perimeter form. From the time the object changed course until it vanished from sight was no more than 2 to 3 seconds. It was traveling at approximately the same speed one might associate with a shooting star - extremely fast. It was a fairly clear night with gusty winds. As the object receded out of sight, I listened intently for any indication of noise. There was none. Given the incredible speed it was traveling, I would have expected a sonic boom. There was only silence. I was by myself, walking the dog at the time of the sighting. While the initial flare of light may have caused others to look up, the remainder of the sight time happened so fast and with such minimal illumination, that it would have taken someone in nearly the same circumstances I was in, to see the same thing. It happened so fast and was obscure enough that it was one of those instances where you had to be at the right place and right time. This sighting took place approximately 45 miles northwest of Ellsworth Air Force Base near Rapid City, SD. I am accustomed to seeing both commercial and military air trafiic in the area at all hours of the day and night. So, it seemed logical that there was a military connection given a flying object and proximity of an air base. However, to travel across 1/4 of the night sky in 4 to 5 seconds is simply impossible by conventional standards. The speed at which it left my sight was so great, it's difficult to effectively describe. The distance away and size of the object are difficult to quantify. Given that it started out appearing as a shooting star the perception was that it was near the edge of the earth's atmosphere. However, as it corrected its course and leveled out, it appeared to be within 3 to 5 miles and roughly the same size, or slightly larger than that of a commercial aircraft. I tried to call the control tower at the air base but was not able to find anyone willing to look into this. I'm not surprised. I would guess that UFO sightings are almost always met with a high level of suspicion and doubt. I have tried to logically explain what I saw and am left with nothing that makes any sense at all. I am a college graduate and active, local businessman. My practical nature begs for an explanation that meets with some earthly criteria. While I am intrigued at the prospect of extra terrestial life, I would best be described as an interested skeptic. Although much of what happened defies explanation, I do know this - I clearly saw an object appear and disappear within 4 to 5 seconds. During that time, I clearly saw a boomerang or delta shape that was covered with soft glowing orange lights. What I saw was moving at a speed that so far exceeds what we are familiar with that it simply was not an aircraft as we know it.