2011-07-27 - Brookings, SD - Circle

White light getting larger, then smaller and fading away

I was driving north, at a speed of 75 mph, on Interstate 29 to my job in Brookings, SD. It was a dark and very clear night with the stars, highly visible. I was about 2 miles south of the Elkton/Sinai, SD exit and came upon a slower car which I decided to pass. Before passing, I happened to look up through my windshield and noticed a bright, white, light to the north about the size of a quarter. My first thought was that it was a plane with his landing lights on heading for the Sioux Falls Regional Airport about 40 miles to the south. I did not see any of the usual strobes on this light and thought that was a little strange but, assumed that it was coming straight south and maybe I just couldn't see them from my position.

I passed this car and a little way ahead was another car going much slower than the one that I had just passed. I looked again, before passing to see if the light was still there. It was but, had grown to about the size of a half dollar and still, I could see no strobes such as aircraft have. I was pretty interested in the light now but, was next to the car I was passing and sped up so I could have a good look at the light. In the matter of seconds that it took to fully pass the car and get back in the driving lane, when I looked up again, the white light had gone from the size of a half dollar to the size of a dime. I turned my attention to the road as I had road construction coming up, then, looked up again. To my amazement, the light had shrunk to the size of a star and then, it was just suddenly gone.

The whole thing couldn't have taken more than 45 seconds. I was fascinated that it had gone from the size of a quarter to half dollar, then to the size of a dime, a star and then just gone, just like that. There was no noise, no contrail, no strobes, etc.

I am familiar with aircraft having grown up near an airport and I am a trained storm spotter and am well aware of atmospheric conditions.