Visually observed a large object passing overhead from straight west to east during the very dark night because of large reddish/yellow or reddish/orange lights. Because if appeared close to the ground in proximity for the size of its shape in the night sky, I stopped my car and got out. I stood and watched it pass overhead at a very low rate of speed. The shape was of a very large triangle object with a pattern of lights under the craft which neither pulsed or blinked. The distance in the dark from where I stood to where the object passed overhead was hard to discern but was far too low to be any kind of large commercial aircraft in a flight path to Sioux Falls, SD airport. It was moving west to east at a very slow speed. As I was just outside the place I work to watch a couple hot air balloons pass by I would estimate that the rate it passed overhead to be 2-3 times the air speed of a hot air balloon. I stood until the object passed nearly out of sight heading toward the Iowa border. I was neither scared or amazed at this, although it never sped up or slowed down during the entire event and as I said was far to close in proximity to the ground to have proceeded north toward the airport in Sioux Falls. That, of course, is just my humble opinion. I have spent a couple occasions looking at various ufo sightings for Iowa and places in the U.S. and some ot the pictures of triangle shaped objects with lights are very similar to what I observed. Don't really know why I have not reported seeing this until now, except that I am 62 years old and I have seen alot in this world anyway. Thanks for your consideration.